Concrete Contractor March 2017 by ForConstructionPros.com

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18 March 2017

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Concrete Durability:

HOW TO AVOID THE DELAMINATION OF STEEL TROWELED FLOORS 10

Can we design and build structures we know will last a hundred years? 22

The Bonds in Diamond Grinding and Polishing Tools

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March 2017 | Issue 2, Volume 17

WHAT’S INSIDE Cover Photo Credit: Joe Nasvik

Departments 4 Editor’s Letter 6 Legal Matters 8 Challenging the System 38 Foundation Q&A 50 The Last Placement

What’s Online

Cover Story

Read these online exclusive articles at www.ForConstructionPros.com/ concrete.

22 When Specifications Require Long Minimum Lifespans

Sid Copeland Water Treatment Plant Undergoes 21st Century Repair

Can we design and build structures to last 50 years, 75 years or 100 years?

Features 10 How to Avoid the Delamination of Steel Troweled Floors Understanding the failure mechanism and causes is the key to avoiding floor delaminations.

14 Planning and Management Software for Concrete Contractors Saving time and increasing productivity.

18 Elegant Concrete Design Greets Patrons at the Hollywood Park Casino Trademark Concrete Systems once again showcases its ability to deliver a unique architectural look with a black and white banded concrete placement in Inglewood, Calif..

28 Specification Guides: Power Trowels A compilation of technical information when choosing your next power trowel.

34 Concrete Repair Keeps Customer in the Cold Repairing an entrance threshold to a cold storage facility doesn’t have to be a disruptive experience.

After a number of repairs throughout the years, the tank had insufficient chlorine contact time because water could “short circuit” the tank. Search: 12311107

The How’s and Why’s of Concrete Curing” Discover ways concrete petrographers evaluate how well (or not) curing operations are done in concrete construction. Search: 12169059

36 Concrete Repair Product Round-up A compilation of concrete repair products.

40 The Bonds in Diamond Grinding and Polishing Tools The key to troubleshooting tooling problems is in understanding the bond.

46 Polished Concrete Maintenance: A Trip Through the Past and A Look at the Future What is the next generation of maintenance products for polished concrete floors and where can contractors find them.

www.forconstructionpros.com/concrete | March 2017 | Concrete Contractor 3

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EDITOR’S LETTER Published by AC Business Media Inc.

Concrete

DURABILITY

ast month I attended the Concrete 2029: Roadmapping Workshop hosted by the Strategic Development Council of ACI. In this session, over 60 attendees were present to listen, learn and brainstorm ideas focused on concrete durability. While there are multiple definitions of durability, it can generally be distilled to: “The capability of structural systems, members and their constituent materials to meet or exceed performance requirements for a set period of time in their service environment.” To open the session, three guest speakers were on hand to discuss various aspects of durability. While each of these presentations offered insight as to what the durability of concrete is and how to define durability. There is no standard or code in place to dictate how durability should be defined. Later in the day, attendees were assigned to break-out groups for further discussion as to how Concrete 2029 can address the topic of durability. While these break-out groups produced a healthy discussion, the end result seemed to produce more questions than answers. The main question at hand as it relates to durability is: “What is the cost of doing nothing versus the cost Facebook.com/ ConcreteContractor

Advisory Board

Ryan Olson, Publisher/ Editorial Director ROlson@ ACBusinessMedia.com (800) 538-5544

of addressing durability and implementing a solution?” Stay tuned, as there is plenty of work to do, before a formal presentation is on the table. The latest Concrete 2029 session could not have been timelier. In this month’s issue of Concrete Contractor, Kevin MacDonald and Joe Nasvik have put together an article addressing this very issue. Turn to page 22 to see their conclusions when we ask: “Can we design and build structures we know will last a hundred years?” To achieve long life requires a special effort on the part of owners, architects, engineers, contractors and material suppliers. The authors explain how current technology is contributing to increasing lifespan, despite lagging questions which don’t seem to have any answers at this point in time.

Kim Basham KB Engineering Cheyenne, Wyo.

Jim Cuviello Cuviello Concrete Polished|Stained|Crafted Stevensville, Md.

Jim Baty Concrete Foundations Association Mt. Vernon, Iowa

Chris Klemaske T.B. Penick & Sons, Inc. San Diego, Calif.

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Published and copyrighted 2017 by AC Business Media Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording or any information storage or retrieval system, without written permission from the publisher. CONCRETE CONTRACTOR (USPS 021-799, ISSN 1935-1887 (print); ISSN 2471-2302 (online) is published 7 times a year: January/February, March, April/May, June/July, August/September, October/November and December by AC Business Media Inc., 201 N. Main Street, Fort Atkinson, WI 53538. Printed in the U.S.A. Periodicals postage paid at Fort Atkinson, WI, and additional entry offices. POSTMASTER: Send address changes to Concrete Contractor, PO Box 3605 Northbrook, IL 60065-3605 March 2017, Issue 2, Volume 17

Search: Concrete Polishing

Dennis Purinton Purinton Builders, Inc. East Granby, Conn. Joe Reardon Diamatic Orlando, Fla.

4 Concrete Contractor | March 2017 | www.forconstructionpros.com/concrete

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LEGAL MATTERS

Concrete Contractors Should Use the New (and Better) I-9 Form Effective January 22, all US employers must be using the new version of Form I-9.

lthough in its simplest format, the form is relatively unchanged, contractors can and should download the form from the US Citizenship and Immigration Services web page and use the new form on a computer. Use this link: https://www.uscis. gov/i-9 There are several reasons why this will work to your advantage. First, the new form will help ensure that you complete the form correctly and avoid common errors. This is so because the form incorporates “built-in” help when you use the computer version. For example, for nearly every blank of the form there is an online help feature accessible through the question mark next to the field title. In addition, if you scroll over a field after a few seconds a help box appears giving advice about what information goes in that field and, more important, how to format that information. Also, using the computer version of the form gives you instantaneous access to the complete 15 pages of instructions, which gives even more detail about how to properly complete the form. The online version of the form also does some of the work for you. For example, when the employee is completing Section 1 of the form

and selects an immigration status, that status automatically is carried forward in Section 2 of the form. There, your choice of documents will automatically be chosen. For example, an employee who checks that he or she is a lawful permanent resident in Section 1, you will not be given a US passport as a document choice in List A of Section 2. Similarly, when completing Section 2 for a US citizen, you should not see a choice for Employment Authorization Document. The online version of the form also has some error checking built-in. If a date is entered in the incorrect format, you will be alerted and given help regarding the formatting issue. Selecting from the document lists ensures that you do not accept or try to record documents that are not permissible. An overarching error checking system exists in the form of a “click to finish” button at the end of each section of the form. Clicking this button results in a powerful review of the entire content of that section, followed by a field by field correction process. When you have corrected the form, you are encouraged to print it out for signature and storage. That is one disadvantage to using this version of the form. You cannot save the data or the completed form online. Still, the new version of the form goes a long way to help ensure that your form is correct and complete. Once you have printed out the form and it is signed, you then can consider electronic storage if desired. The new form also has a new area in Section 2 for additional information relevant to the I-9 process. For

David C. Whitlock has over 25 year’s experience in business immigration, compliance, employment counseling and training. He is the founding attorney of Whitlock Law LLC and can be reached at (404) 626-7011 or at davidcwhitlock@gmail.com.

example, you can use this area to record termination dates and form retention dates. Also, new to this version is the ability to record more than one Preparer/Translator if necessary. There is a separate supplement that can be used for this purpose and you can use it multiple times, so in theory any number of persons can assist the employee in completing Section 1 of the form. The system is still not perfect. No changes have been made to the document list, which is attached to the online version of the form. Thus, the list still has things in the wrong columns and way too many documents. On the other hand, the document list attachment is a little bit more helpful in terms of understanding what the documents are. The instructions misstate the regulations with respect to the timeliness of completion issue. The instructions have a clear example that gives you four days to complete the form. You are told that for someone who starts work on Monday, you must examine documents and complete Section 2 by the close of business Thursday. That is contrary to the regulations which define “hire” as the commencement of work for pay and require completion of Section 2 “within three business days of the hire.” You can still use the “paper” version of the form. You can download that from the same website and photocopy it as necessary. It is hard to ignore all the good help that comes built-in to the new version, though. Try it and see. You can always go back to the “paper” version.

6 Concrete Contractor | March 2017 | www.forconstructionpros.com/concrete

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Ward R. Malisch, PE, PhD, FACI is concrete construction specialist for the American Society of Concrete Contractors. Reach him at wmalisch@ascconline.org.

CHALLENGING THE SYSTEM

Concrete Slump Should Not Be Specified

Bruce A. Suprenant, PE, PhD, FACI, is technical director for the American Society of Concrete Contractors. Reach him at bsuprenant@bsuprenant. com.

The concrete producer and contractor should determine slump requirements.

he floor placement is running smoothly. Concrete slumps have ranged from 4 to 6 in.—the specification requirements—and the last truck is on site with about 12,000 cu. yd. of concrete on the ground. But then a slump test on that last truckload yields a 6 ½-in. result, verified by a retest. The inspector rejects the load. No more trucks are scheduled to arrive, and the plant has closed. A disaster? Maybe not. But it’s almost certainly an unnecessary and costly delay if the contractor tells the plant to re-open and waits an hour or more, with the threat of a cold joint looming. And if the contractor chooses instead to place 6½ in.slump concrete instead of waiting, there’s another problem. Most inspectors believe there is no choice in this case. The slump is ½-in. over the maximum value, so they note the non-conformance in their daily report. That can then result in a dispute about potentially poor performance of that last truckload. This is not a problem with a do-it-bythe-book inspector. It’s a problem with the specification. For many years, after the first ASTM procedure for slump was published in 1922, concrete specifications included requirements for either a maximum slump or a slump range. The belief was that higher slumps indicated lower concrete strengths, and the test could thus

be used to prohibit high-slump and allegedly low-strength concrete from being placed in pavements or structural elements. But the rationale for using slump as a strength indicator is no longer valid.

EARLY USE OF THE SLUMP TEST The 6th edition of the Portland Cement Association’s Design and Control of Concrete Mixtures (1940) stated that the slump test was a rough measure of consistency—a general term meaning fluidity or wetness. It cautioned that: “This test was not an absolute measure of workability and should not be used to compare mixes of wholly different proportions or of different kinds of aggregates. Under conditions of uniform operations, however, changes in consistency as indicated by the slump are useful in indicating changes in the character of the material, the proportions or

the water content.” Surprisingly, the recommended slumps for concrete were quite liberal, as follows: • Massive sections, pavements, and floors laid on ground: 1 to 4 in. • Heavy slabs, beams or walls: 3 to 6 in. • Thin walls and columns, ordinary slabs or beams: 4 to 8 in. This was in an era when concrete for building construction contained only cement, water, and fine and coarse aggregate. So an 8-in. slump was produced with water to yield concrete strengths in ranges from 2500 psi—w/c = 7-3/4 gal/sack (0.68 by weight)—to 3750 psi—w/c = 6 gal/sack (0.53 by weight). The 6th ed. also contains a suggested specification for plain and reinforced concrete, with quality based on the water-cement ratio and proper workability. Slump limits were not specified, however. The specification required: “The proportions of aggregates to cement for any concrete shall be such as to

KINDS OF CONSTRUCTION

MAX. SLUMP

MIN. SLUMP

Reinforced footings

3 in.

1 in.

Plain footings, caissons, substructure walls

3 in.

1 in.

Slabs, beams, reinforced walls

4 in.

1 in.

Building columns

4 in.

1 in.

Table 1

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Table 2

produce a mixture which will work readily into corners and angles of the forms and around reinforcement with the method of placing employed on the work but without permitting the material to segregate or excess free water to collect on the surface.” By 1960, ACI Committee 301 (401) had prepared a suggested Specification for Structural Concrete for Buildings, which was presented as a progress report at the March 1960 annual ACI convention. This document and future versions had significantly reduced the allowable maximum slump and slump range for vibrated concrete as shown in the table. The decrease in maximum allowable slump was probably based on the assumption that higher slumps indicated higher water contents that resulted in poor quality concrete— lower strengths and water tightness. That, however, would have assumed that cement content was constant and all other factors affecting slump hadn’t changed—not a bad assumption for the 1960s. Today it’s a bad assumption. Daczco reported on results of many tests conducted on concrete mixtures made with essentially the same water and cement contents, no admixtures, but sands from two sources. Note the slumps for the following two mixtures: The higher slump concrete has the same water content and paste content as the lower slump concrete. Other factors are at work.

THE SITUATION NOW Even with no change in water content, other variations in aggregate grading, fines content (cement and supplementary cementitious materials), entrained air content, and especially water-reducing admixtures, can have a major effect on slump and slump loss. So slump is no longer a good indicator of hardened concrete quality. The ASTM Test Method for Slump of Hydraulic-Cement Concrete (ASTM C143) now states the following in Note 1, of Section 4.1: “This test method was originally

MATERIAL

BATCH WEIGHT IN LB

Sand 1

Sand 2

Cement

654

656

Fine aggregate

1277

1301

Coarse aggregate

1811

1816

Water

322

323

Slump, in.

5.25

8.25

Air content, %

1.5

1.2

Fresh concrete properties

developed to provide a technique to monitor the consistency of unhardened concrete. Under laboratory conditions, with strict control of all concrete materials, the slump is generally found to increase proportionally with the water content of a given concrete mixture, and thus to be inversely related to concrete strength. Under field conditions, however, such a relationship is not clearly and consistently shown. Care should therefore be taken in relating slump results obtained under field conditions to strength.” Slump does affect the ease with which concrete can be transported, placed, and screeded, and is a fairly reliable indicator of batch-to-batch variability. That makes it important to contractors who have to place and finish the concrete. Concrete floor construction, for instance, requires tight slump control when very flat floors are specified. A high-slump truckload in one area of the floor can result in delayed finishing and difficulty in achieving specified flatness, whereas a low-slump truckload can cause placing difficulties and delays on jobs where the concrete is pumped. Slump is also an important factor in placing structural members such as columns and walls since it affects the ease with which the concrete can be placed and consolidated to minimize honeycomb and bugholes. Thus, it’s in the contractors’ interest to control slump and other properties of fresh concrete. They need to work closely with their concrete producer to achieve slumps within an agreed upon range. But that

range should not be included in the specifications because specifications are needed to control performance of the hardened concrete; tests for compressive strength and air content are currently the best means for controlling both strength and durability of concrete. For more than 10 years, the National Ready Mixed Concrete Association has been advocating for the use of performance rather than prescriptive specifications. Their belief is that some requirements in prescriptive specifications are not needed. Slump is one of these. They believe as we do, that a partnership between the concrete contractor and concrete producer should be responsible for setting the slump range. In 2012, ASCC and NRMCA produced a Checklist for Concrete ProducerConcrete Contractor Fresh Concrete Performance Expectations. This checklist is used to establish concrete producer’s and contractor’s responsibilities for expected concrete properties and placement methods before the first pour. Then, in cases where the slump exceeds an agreed upon maximum, contractors instead of inspectors can weigh the pros and cons and decide on the course of action. If there’s any doubt about quality of the hardened concrete, making and testing a set of cylinders could be an option. But rejecting a load of concrete based only on slump is supported now by beliefs from the past, and nothing more. That’s a good reason for deleting slump requirements from specifications.

www.forconstructionpros.com/concrete | March 2017 | Concrete Contractor 9

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FLATWORK/SLABS

Kim Basham, PhD PE FACI

How to Avoid the Delamination of STEELTROWELED FLOORS Understanding the failure mechanism and causes is the key to avoiding floor delaminations.

elaminations are horizontal separations of the top surface of a floor slab from the underlying concrete. Typically, delaminated thicknesses vary from about 1/8 to 3/8 inches but can be thinner or thicker depending on the cause of the delamination. Unfortunately, surface delaminations are difficult to detect during the finishing operations but become apparent later after the concrete has hardened or shortly after the floor has been placed into service. In some cases, workers including electricians or plumbers discover delaminations during construction by dropping tools or other items on the floor and hearing a “hollow” or “tinny” sound. Hollow sounds indicate the top surface of the floor has separated from the underlying concrete. “Sounding” by either tapping with a hammer or dragging a heavy chain and listening to the resulting sound are the easiest and primary means to detect and map delaminated floors. In fact, sounding is a recognized and standard means to detect surface delaminations of concrete.1 More sophisticated means of detecting surface delaminations include impact echo and ground-penetrating radar. Delaminations are typically limited to areas of a few square feet distributed randomly over floors. However, larger delaminations can be widespread over entire floors, requiring overlays and full-depth slab

replacements. It is better to understand the failure mechanism and causes so you can take the appropriate actions to avoid surface delaminations of steel-troweled floors.

DELAMINATION MECHANISM As illustrated in Figure 1, delaminations typically occur because of a weak zone located directly below a densified surface layer (DSL) that fractures along a horizontal plane allowing the top surface of the floor to separate from the body of the concrete. When bleedwater migrates upward because the cement and aggregate particles are settling, the surface must be “open” so as not to trap the rising bleedwater and air directly beneath the top surface. As shown, trapping bleedwater and air creates a thin, weak layer directly beneath the DSL. Due to concrete drying shrinkage at the surface and/ or loading of the floor, fractures grow horizontally in the weakened layer and the top surface delaminates or separates and becomes detached from the body of the concrete. Incipient or developing delaminations may sound solid when tapped with a hammer or chain dragged because the densified surface layer is still somewhat attached to the underlying concrete. However, fractures in the weakened layer may grow due to floor loading, especially forklift traffic.

TRAPPING BLEEDWATER, AIR The top surface of the floor must remain open during the concrete’s

Surface delaminations are separations of the top surface from the underlying concrete. Photo Credit: Kim Bahsam

bleeding phase so that bleedwater and air can rise and freely escape to the top surface of the slab. If the surface becomes ‘”closed” by sealing or densifying from improper or premature finishing, top-down setting or surface drying (i.e., crusting) while the concrete is still bleeding, bleedwater and air can become trapped below the surface creating the weakened zone that leads to delaminations. Improper or premature finishing, top-down setting and surface drying essentially change or decrease the permeability along the top surface of the concrete so rising bleedwater and air become trapped below the less permeable concrete layer. Improper finishing typically consists of using the finishing tools with too steep of angle during bull floating, floating or troweling. As the angle of the tool or blade increases, the pressure applied to the surface also increases. Too much pressure applied too soon densifies and seals the concrete along the top surface of the slab. Keep bull floats and floats as flat as possible to minimize the pressure applied to the concrete. Only when the concrete surface stiffens sufficiently from the chemical hydration of the portland cement (not surface drying) should the angle

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FLATWORK/SLABS of steel float or finishing blades be increased to start the densification process of the top surface. Premature finishing occurs when the densification process of the top surface starts before the cessation of bleeding. If finishers start the densification process too soon, rising bleedwater and air become trapped below the DSL. Finishers must exercise caution not to start the finishing or densification process when the surface appears ready to finish because of top-down setting or surface drying. If the evaporation rate exceeds the bleed rate and there is no water sheen on the concrete, the surface may appear ready to finish but if the concrete is still bleeding, it is too early to start densifying the surface. Top-down setting occurs when bases and subgrades are colder than air temperatures so the concrete along the base sets slower than concrete along the top surface. The more plastic and slower setting concrete along the bottom is still bleeding so that bleedwater becomes trapped below the stiffer or faster setting concrete along the top surface. To protect against top-down

Chain dragging is an easy means to detect floor delaminations. In most cases, small irregular surface cracks occur in the delaminated surfaces. Photo Credit: Kim Bahsam

setting consider warming bases and subgrades so the entire thickness of the concrete sets more uniformly. Similar to top-down setting, bleedwater rising from plastic concrete can become trapped below a crusted surface. To avoid surface drying and crusting, use water fogging

or apply a spray-on evaporation retarder to protect the surface from premature moisture loss between the finishing operations. Thicknesses of delaminated surfaces may exceed the typical 3/8 inch for delaminations caused by topdown setting and surface crusting. Delaminated thicknesses typically reflect the extent of the top-down setting or surface crusting that occurred. In addition, to the formation of a weakened layer, a separation or gap may form between the stiffer upward layer and the more plastic lower level of concrete due to differential settlement related to differential bleeding.

RISING BLEEDWATER Since rising bleedwater and air create the weakened layer that leads to delaminations, any factor that increases the rate, capacity and duration of bleeding increases the potential for surface delaminations. Factors include: cold bases and subgrades, placing concrete directly on a vapor barrier, thick slabs, concrete with high water contents, entrained air content approaching or above 3%, some chemical admixtures and supplementary cementitious materials (fly ashes and slags) that delay concrete setting, and ambient conditions including wind, low relative humidity, direct sunlight, and rising air temperatures. Of the factors listed above, wind requires special consideration. As wind speeds increase, the bleeding rate, capacity and duration of the concrete also increases. For every 5 mph increase in the wind velocity, the bleeding rate, capacity and duration increase about 25 percent.2 Therefore, wind significantly increases the risk of delaminations by increasing the risk of surface crusting and the rate, capacity and duration of bleeding. Purposely entrained air and other chemical admixtures that create microscopic air bubbles approaching and exceeding 3% (total air content) significantly increase the risk of delaminating steel-troweled concrete. Microscopic air bubbles slow the rate of rising bleedwater and air

As seen under the microscope, trapping bleedwater and air below the top surface of the concrete typically creates a weakened layer that fractures allowing the top surface to break away from the underlying concrete. Photo Credit: DRP Consulting, Inc.

so the surface may appear ready to finish and densify but bleeding is still occurring. Subsequently, finishers prematurely seal the surface creating the weakened layer directly below the DSL. For these reasons, air-entrained concrete should not be steel troweled.3 In addition, finishing operations can crush and coalesce the microscopic air bubbles so that elongated air voids form in and just below the DSL increasing the risk of surface delaminations. When air voids are located in and directly below shallow densified surface layers, thicknesses of the delaminations can be very thin or less than 1/8 inch. In summary, finishers must be aware of any actions or conditions that will seal, densify or reduce the permeability of the top surface of the concrete as compared to the underlying concrete. Finishers must also consider factors that may increase the rate, capacity and duration of bleeding. By considering both issues, finishers can alter or adjust the concrete mixture, jobsite conditions and timing of the finishing operations to avoid surface delaminations. References 1. ASTM D4580 Standard Practice for Measuring Delaminations in Concrete Bridge Decks by Sounding, American Standard Testing and Materials, www.astm.org 2. Tarr, S. M. and Farny, J. A., Concrete Floors on Ground, 4th edition, Portland Cement Association, 2008, www.cement.org 3. ACI 302.1R-15 Guide to Concrete Floor and Slab Construction, American Concrete Institute, 2015, www.concrete.org

12 Concrete Contractor | March 2017 | www.forconstructionpros.com/concrete

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CONTRACTORS Saving time and increasing productivity.

USING CONSTRUCTIBLE BIM

hese days, when a construction company, especially a small construction company, provides a bid for concrete walls or foundation walls, they typically receive PDFs (portable document format) instead of plans to bid from. However, some contractors are hesitant to use PDFs because information is often incomplete. But most end up using them to calculate the amount of concrete, steel reinforcement and other related materials, add an amount for labor, forms, and profit and submit their price. If they are awarded the project, office staff constructs shop drawings, start planning for the construction, do layout work and set up

cost-accounting procedures. In this process, a lot of time and effort goes into estimating, planning, doing layout work and managing concrete placements—some of it being redundant. So with this in mind the Trimble Corporation based in Santa Clara, Calif., decided to build onto their Tekla software (software that uniquely serves the concrete industry) to provide concrete contractors with easy-to-use software that plans for and manages all aspects of the forming and concrete placement process. Their one-of-a-kind product is useful for both small and large companies—from residential foundations to large commercial projects.

The concept of Building Information Modeling (BIM) goes back to the 1970s but the technology didn’t become useful for managing building projects until the early 2000s when the technology was developed better and contractors began to use it. BIM makes it possible for contractors to create three dimensional digital images of their work, accurately plan for the materials they need, and collaborate with other team members throughout the life of the project. For many this happens when estimates for new work are being created. It speeds up the estimating process and facilitates the next steps in the beginning construction process; material orders, planning, doing layout work, scheduling with other trades, cost accounting and many other features. Companies that use BIM are able to eliminate many repetitive tasks and be more productive. Also, it’s very easy to create points and send them as digital files to robotic total stations for laying out points and elevations for the structure being built. Digital files sent to robotic total stations can also be used to direct site excavation and grade preparation machines. BIM is now a part of the construction mainstream. When contractors create 3D digital BIM images of their projects they can use them to estimate, plan, do layout work, design the forming system needed, manage, and cost account. Photo Credit: Tekla

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CONSTRUCTIBLE BIM FOR FORMWORK From the beginning Tekla software focused on the concrete construction industry, so a logical next step for them was to design software that added forming technology to their established BIM product. Andy Dickey, the cast-in-place concrete business development manager for Trimble’s structures division, says they wanted the new formwork offering to be useable for big and small contractors—software that they could easily use themselves. They wanted it simple enough for contractors to quickly build their own 3D models and digitally lay out formwork with the same forming system they planned to use for the project. For small contractors, the owner is typically the one who learns how to use the software and for larger companies it’s their estimators, project engineers, or project managers who do the work. Dickey says contractors

When planning the formwork for a job, management selects the forming system they will use for a project in the “digital warehouse” folder in the software. To automatically place the forms, you swipe your form choice along the digital wall or foundation wall model you created. The software shows the form assembly. Photo Credit: Tekla

also save money using BIM software by eliminating many repetitive tasks. In the process of construction, Tekla software takes you through several steps. The first step is typically the construction of a 3D model during the estimating phase of a project to determine areas, volumes and lineal amounts of the materials needed for bidding the job. When the job is contracted the next step is to add the forming system chosen for the work. The software provides

considerable automation to help make this step easy. Part of the new formwork offering includes a “formwork warehouse,” where information about each recognized manufactures’ forming systems, along with some generic systems are represented. “At present we have both Peri’s and Doka’s forming systems (two of the largest forming manufactures in the world) cataloged in the system, as well as a couple generic ones,” Dickey says.

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FOUNDATION/WALLS “Eventually we will have almost all form manufacturers products stored.” To automatically place forms for your project, you select the forming system you are using and swipe it along the digital wall or foundation wall model you created for your bid. The software provides you with a 3D view showing the forms assembled in place as they should be laid out. Work crews can use this as a shop drawing; easily sent to iPads or jobsite tablets so they can see how the forms should be assembled. If you prefer traditional formwork drawings, Tekla software can be used to automatically produce a 2D formwork drawing set too. All forming systems include ties and bracing systems so there is common logic for the software to use. This made it easy for Tekla to automate the placement of formwork in BIM drawings. For example, when you select the form manufacturer and the forming system you are using for

After constructing 3D digital image contractors can use it to lay out points with a Total Station. Photo Credit: Atlantic Concrete

your project the software automatically places pins and clamps wherever you wish. It also installs braces and brackets where they should be located for the proposed wall. Dickey adds that if you change your concrete placing locations or placing schedule, brace and bracket locations may be easily changed to accommodate these changes.

WORKING WITH THE PROGRAM John Sadosky, owner of A&J Concrete, Las Vegas, Nev., specializes in commercial concrete work and occasional high-end residential. He says they started using Tekla software about three years ago to model concrete and rebar for their projects. He thinks the software is amazing and keeps getting better in terms of

functionality. When they are working on estimates they create models to determine material quantities. “Having the model makes it easy to communicate with the architect and engineer for a project when we have questions or need clarification,” he says. When they develop a model for estimating purposes they bring it to a certain point. Later, when they are contracted for the work they add to the model without redoing anything. They go on to use the model for setting points with total robotic stations, locating mistakes before construction starts, planning concrete

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placements and monitoring work. Sadosky says there are four people in his company that use the software, including himself.

WHO THE SOFTWARE IS INTENDED FOR If you are a residential foundation contractor and you frequently encounter projects in hilly areas where there are frequent elevation changes for footings and forms, Tekla’s new wall forming software can be very helpful and save you a lot of planning time. Foundation contractors who specialize in custom home

construction will benefit also. For many commercial projects contractors often rely on their forming manufacturer to provide them with form layout drawings for their project. But there can be time delays when manufacturers get backed up with requests from many contractors all wanting information at the same time. This serves as an added incentive for contractors to learn how to use the software and do their own digital layouts. If a project is large enough to include different concrete mix designs for portions of a structure, this software allows you to manage the project by mix design also. This is made possible with Trimble’s patented concrete placing, planning and management technology.

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technology, is perhaps what slows down growth the most in the construction industry. Bigger companies try to minimize this unwillingness by hiring students fresh out of college who are trained to use it in school or by hiring professionals who already know the technology. However, smaller companies often don’t have that ability, they must provide opportunities for existing staff to be trained and coached. Recognizing this, Dickey says they offer a range of training opportunities that include class training, on-site learning and on-line training. Companies can also pay a yearly fee for phone access to a “help desk” to assist staff when they need it. The software can either be purchased or rented. For a quick way to visualize how the new software works see YouTube - Concrete Formwork Planning Made Quick and Easy.

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www.forconstructionpros.com/concrete | March 2017 | Concrete Contractor 17

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DECORATIVE CONCRETE

By Greg Udelhofen The black and white banded design creates a dramatic grand entrance to the casino.

Elegant Concrete Design Greets Patrons at the

HOLLYWOOD PARK CASINO Trademark Concrete Systems once again showcases its ability to deliver a unique architectural look with a black and white banded concrete placement in Inglewood, Calif.

ollywood always conjures up images of the red carpet walk and lots of glitz. While you won’t need a tux or evening gown if you’re stepping out for a night of fun at the Hollywood Park Casino, you will be impressed when arriving at the main entrance.

Clean saw cuts provide a crisp definition of the contrasting bands.

That’s thanks to the beautiful execution of the geometric black and white design created by Southern Californian architectural concrete specialists, Trademark Concrete Systems. The casino is part of the 300acre development where the new Los Angeles Stadium, home to the Los Angeles Rams and Los Angeles Chargers, will be completed in time for the 2019 season. The new casino replaces one that had to be demolished for the stadium project. Needless to say, the casino was a fasttrack project that had to be completed by the fall of 2016 in time for the stadium groundbreaking ceremony. Kyle Boyer, project manager for the casino project, and Chris Wolf, project superintendent, say Trademark is accustomed to delivering high-quality projects on a tight deadline. Trademark has built a strong reputation by delivering highend decorative concrete projects at world-class resorts and hotels, museums, entertainment centers, major universities, office buildings and retail centers. The company’s community involvement is evident through the decorative work done at parks, schools, street improvements and churches.

The architect, Mia Lehrer & Associates, specified the cast-inplace banding design of the vehicular portico emphasize a strong contrast between the black and white colors simply by requesting the white to be as white as it can be and the black to be as black as it can be. White aggregate, white sand and white cement were used for the white bands, while a Davis Dark Gray 860 integral color and a charcoal color hardener were used for the black bands. The most significant challenge on the project was matching a reverse of the pattern in the lobby area.

PROJECT EXECUTION So how do you begin executing a 12,000-sq. ft. intricate design? Trademark poured a 6-by-6 foot black square. With that in place and through a series of 12 different pours, the crew working on the project began placing 6 ft. wide bands outward, only placing two sides of each concentric box in a pour to avoid corner cracking. Each pour was saw cut the following day with a single 1/8 in. wide blade to control cracking, before the adjoining sides of each square were poured. Once all the black banding on the exterior of the entrance was completed, members of the crew repeated

18 Concrete Contractor | March 2017 | www.forconstructionpros.com/concrete

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DECORATIVE CONCRETE

The decorative pattern is reversed on the inside of the entrance.

the process with the white banding. Once the exterior white banding was completed, crews used a 3/16th in. wide blade to double cut the initial joint cuts to achieve a clean and crisp line between the color bands. Completing the interior portion of the concrete banding was delayed a couple of weeks to allow a lighting contractor time to hang at intricate chandelier in the lobby. Trademark did not want heavy lift equipment being used on a fresh pour, so decided to wait for the lighting contractor to finish. The challenge inside was matching the saw cut lines on the reversed pattern with the exterior portion of the project, which was separated by the 6-in. wide entry wall. As Wolf points out, “It was pretty typical project for us, one that required us to make sure the layout was correct before beginning, especially when it comes to lining up the saw cuts on the other side of a glass wall. It would be very noticeable if those cuts didn’t exactly align.” Waiting for other subcontractors reduced Trademark’s time to complete the front entrance portion down to three weeks.

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With black concrete bands covered, workers place white concrete.

SOME BASIC GOOD WORK Along with the intricate detailing of the casino’s grand entrance, Trademark installed an additional 15,000 sq. ft. of natural gray Eco cast-finished decorative concrete around the perimeter of the casino, which took approximately six weeks to finish based on when areas of the project were ready for sidewalks to be installed. When completed, both portions required three-miles of saw cuts with the initial single cut and final double cut, and the Trademark crew, according to Boyer, “exceeded the expectations (of the general contractor) by delivering our project ahead of deadline, even while accommodating the needs other contractors working on the project,” Boyer notes. “That’s how we approach and deliver every project and that’s what we’ve been doing since 1997.

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www.forconstructionpros.com/concrete | March 2017 | Concrete Contractor 21

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COVER STORY

By Joe Nasvik and Kevin MacDonald

When Specifications Require Long Minimum LIFESPANS Can we design and build structures we know will last a hundred years? As the cost of building structures increases owners such as Department of Transportations’ want them to last longer so they include language in specifications requiring lifespans as much as 100 years. Construction costs more but they hope that maintenance over the years will be less. Photo Credit: Joe Nasvik

ow long should a concrete structure last? Owners are asking that question and it’s natural to want them to last a very long time, especially structures which are very expensive to build. So they are beginning to specify and expect minimum life spans as much as 100 years without unusual maintenance requirements. This can be a daunting task, especially when parts of a structure are exposed to harsh elements such as bridges and decks exposed to large volumes of deicing salt and extraordinary freezethaw cycling each winter. To achieve long life requires special effort on the part of owners, architects, engineers, contractors and material suppliers. Contractors are often awarded design-build contracts to do the work and therefore bear most of the responsibility to prove to the owner before the contract is awarded that the structure will perform as planned. Specifying the long life of a structure usually involves focusing on the

elements of a structure that have the highest level of risk associated with them. Rarely is money spent to maximize all parts of a structure because the cost would be prohibitive. For example, if the foundations for a structure are constantly submerged in brackish water, it’s reasonable to allocate more funds to include higher durability concrete in the foundations. Further, if they had to be repaired at some future time the cost would be very high, given their location. As the life expectancy requirements for a project goes up so does the risk because solutions tend to fall outside the norms. Here are some thoughts about balancing structural concrete durability with cost and risk between owners and contractors.

WHAT THE OWNER WANTS The movement to specify longer service life elements probably started with Departments of Transportation (DOT) evaluating or critical expensive bridge construction projects. Ed Lutgen, the State Bridge Construction and Maintenance

Engineer for the Minnesota Department of Transportation (MnDOT) says they needed to increase the lifespans of some of their more expensive bridges and they recognized they could only do this by encouraging creativity on the parts of all the participants of a project and by trying new technology and ideas. One way to achieve this is by using design-build type contracts so that contractors have the freedom to suggest newer technology and different designs. “As an agency MnDOT works to improve quality, durability and least cost ownership. We know that experimental approaches works both ways, some ideas achieve the goals we have set but some don’t and MnDOT accepts that mistakes will sometimes happen but the risk of doing nothing is greater,” Lutgen adds. MnDOT specified 100 year service lives for the I-35W bridge over the Mississippi River in Minneapolis (the old bridge collapsed in 2007) and the new pre-cast segmental “extra dosed” bridge crossing the St. Croix River at Stillwater. Usual construction materials and methods specifications for bridges couldn’t achieve this lifespan so project participants; including design, engineering and contractors were invited to submit ideas for consideration. Contractors were also focused on constructability. MnDOT

22 Concrete Contractor | March 2017 | www.forconstructionpros.com/concrete

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COVER STORY sees this process as the best way to accommodate innovation. Lutgen says that in the ideal world owners would like others to warrant or guarantee their work for the specified lifespan of a project but they recognize this isn’t realistic. If it could happen, projects would become too expensive to build because construction teams would want to pass on the costs for bonds needed to back up the warranties. One way to avoid this conflict is to require a maintenance contract for the structure over the first several years of construction, or to enter into Public-Private Partnerships where the design builder is also owner and operator. This can involve tolls or a fixed fee from the DOT.

WHAT DETERMINES STRUCTURAL LIFE Some parts of a concrete structure are always more vulnerable to premature aging than other parts. Elements exposed to severe environments are where costly repairs occur. Traditional contracts between owners and contractors typically don’t encourage anyone to come up with better approaches. Some environments that reduce concrete service life include the following: • Concrete exposed to multiple freeze-thaw cycles each year • Salt water environments—pavement and bridges exposure to deicing salts and ocean saltwater spray on bridge piers and other parts. • Footings and foundations submerged in brackish water • High wind loads on super-tall buildings and other structures • Lack of protection for steel reinforcement • Fires and blasts • Excessive loads

BREAKTHROUGHS When you are challenged to extend the life of a structure, you must focus on what is presently known and future predictions.

Building a super-tall building is a good example. High-rise structural concrete buildings are typically designed to withstand a minimum 50-year wind event but super-tall buildings (most all are structural concrete constructions now) are so expensive and pose so many additional challenges that owners and engineers plan on a minimum 100-year wind event and models are subjected to wind-tunnel testing during the design process. Newer technology helps to increase lifespan. Here are some examples: Software It helps design and construction at every level. Engineers use several software programs to analyze the behavior of structures under every condition available and plan for reinforcement. Contractors use programs such as building information modeling (BIM) to model and understand their work better: analyze, schedule, detect conflicts, do layout work, order materials and cost account. Reinforcement. Often the “Achilles Heel” for concrete, when reinforcement corrodes and expands concrete, deterioration follows. Fiberreinforcement polymer (FRP) rebar, stainless steel rebar, pre-stress and post tension reinforcement, and fiber reinforcement are ways to limit corrosion. Electronic monitoring. Knowing how a structure behaves over time builds on our body of knowledge and provides early warning to maintenance issues. Electronic sensors can measure stress, chloride penetration, moisture content, temperature and vibration. Modelling. The industry has developed a number of models to simulate the performance of structural elements on the basis of exposure and transport properties of the concrete. This is essentially the same process used for structural design. The Engineer

constructs a mathematical model based on the environmental loads, dimensions and material properties. The lack of a North American based code complicates this modelling, as the fib 34 model relies on the NT Build 492 testing that does not have an ASTM equivalent. Contracts Integrated project delivery (IPD), design-build and performance contracts are ways to encourage more innovative approaches. When contractors suggest creative solutions, new owners may require assurance in the form of warranties.

HOW TO ACHIEVE A 100 YEAR SERVICE LIFE There are a number of ways to increase the durability of concrete and therefore its service life. When designing concrete mixes consider the following: • Use non-reactive aggregate • Limit concrete shrinkage • Use well-graded mixes with the largest top-size aggregate possible • Design high density mixes • Design mixes so that large aggregates are in contact with each other • Include pozzolans and keep total cementitious weight as low as practical. Cement paste should be kept to the minimum amount required to fill the voids in the aggregate and a small fraction to allow flow. • Keep water-cement ratios low to

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It’s best to invest more money for elements of a construction that are the most susceptible to problems. Decks pose the biggest problems for bridges, so engineers included post-tension reinforcement (inside the plastic ducts) to prevent cracks which would permit water to reach the reinforcement on this very high-traffic deck. Photo Credit: Joe Nasvik

provide an acceptable diffusion value. Steel reinforcement in concrete must be kept dry and chloride free. Once the chloride ion content is high enough, steel corrodes and expands, breaking up the concrete surrounding it. The best way to prevent moisture from penetrating concrete and wetting reinforcement is to use high density concrete mixes, provide adequate concrete cover, and keep cracks small enough to prevent water penetration. Lutgen says MnDOT decided to replace steel rebar with stainless steel in bridge decks to avoid the corrosion problem. “Reinforcement costs up to four times as much but that is justified by low maintenance costs in the future.” Post tension reinforcement is another way of preventing crack development in decks. Also, adding fibers to concrete is a way to prevent cracks from becoming wide enough for water to penetrate. Monitoring structural concrete in buildings isn’t as important as it is for bridges because it is sheltered from the elements by the buildings curtainwall. Monitoring long lifespan structures that are exposed to the elements is more important and should start at about 10 years. Information learned when a structure is at 10 percent of its rated life should provide information about how it will behave for the rest of its life. Testing should include removing cores, electronic testing, and lab tests related to environmental exposure.

CONTRACTS AND WARRANTIES Lutgen says MnDOT is one of the more progressive DOTs in the US in terms of its commitment to increasing the lifespan of its bridges and

pavements. So they like design-build contracts because contractors have the opportunity to be more innovative in their approach to building high-traffic and more expensive bridges that will last longer. Typically contractors provide a plan along with their price that explains how they will meet life expectation requirements. Ideas are discussed and agreed upon

by both sides before a contract is issued. Testing is part of this process too. But MnDOT understands that the level of risk goes up too for some innovative approaches so they want the contractor to warrant their ideas for a period of time—usually three to seven years.

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SPECIFICATION GUIDE: POWER TROWEL

Power Trowel

A compilation of technical information when choosing your next machine.

1 Allen HDX760 Ride-On Trowel

Allen, a manufacturer of site prep and concrete finishing equipment, announces the debut of their new HDX760 Riding Trowel. The HDX760 is a state-of-theart, hydraulically controlled ride-on power trowel that incorporates “IntelliPower” to ensure peak performance, component safety and extended life. The built-in “Intelli-Power” system controls both the hydraulics and the engine operation. With “Intelli-Power” the 74 hp T4F Hatz diesel engine and the Bosch-Rexroth hydraulic components actually talk to each other to ensure maximum performance and safety at all times. This results not only in performance unequaled by competitors and safety protection for these very critical engine and hydraulic components, but also much longer operating life expectancy. The “Itelli-Power” system is a combination of the Bosch-Rexroth hydraulic control unit (HCU) and the Hatz engine control unit (ECU). The HCU communicates with all of the pumps, motors and valves to ensure maximum performance and safety. It also monitors the hydraulic filter to warn when the filter is clogged, and monitors the hydraulic temperatures to prevent component damage. The ECU works with the HCU to maintain maximum efficiency and precise rotor speed. It is able to sense the engine load and adjust the rpms to prevent the engine from bogging down, and all the while keeping effective rotor speeds on the concrete. ForConstructionPros.com/12287253

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

HDX760

Ride-On

2,687

117.6”

145

Hydrauilc

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

Pro446

Walk-Behind

250

46”

120

Manual

Handle Options

(Walk Behind Only)

N/A

Handle Options

(Walk Behind Only)

Fine Pitch or Positive Pitch

Engine HP

Fuel Type

Diesel

Engine HP

Fuel Type

Gas

Engine HP

Fuel Type

2 HoverTrowel Pneumatic Walk Behind Models

Weighing less than 45 lbs., the HoverTrowel is a patented power trowel designed for finishing polymer toppings. Interchangeable high and low pneumatic motors make it ideal for most of today’s polymer toppings. A six-position telescoping handle, coupled with interchangeable guards creating 25” and 34” trowel paths make this trowel easy to maneuver in confined spaces and wide open areas. A HoverTrowel can be used for most epoxy, cementitious urethane, polymer modified, EPDM rubber and many other hybrid toppings with a variety of blades and floats. Its design makes these pneumatic motors easily interchangeable with the company’s four-cycle engine as well. ForConstructionPros.com/12039894

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

High Torque Air

Walk Behind

25” or 34”

0-60

Mechanical

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

Low Torque Air

Walk Behind

25” or 34”

0-60

Mechanical

Handle Options

(Walk Behind Only)

Telescoping

Handle Options

(Walk Behind Only)

Telescoping

I-R .76 hp Pneumatic

Engine HP

Fuel Type

I-R .41 hp

Pneumatic

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3 EDCO T364 Walk-Behind Trowel

The model T364 is a 5.5 hp gasoline unit with an optional Leveling System for smooth troweling. It has a 36-in. troweling diameter, standard Lifting Bail and features bolt-on blades. ForConstructionPros.com/12039874 Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

T364

Walk-Behind

186

36”

118

N/A

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

T-364-3

Walk-Behind

192

36”

115

N/A

(Walk Behind Only)

Handle Options

Engine HP

Fuel Type

5.5

Gas

(Walk Behind Only)

Handle Options

Engine HP

Fuel Type

Electric/230 V

4 LR Tools Power Pole Finisher

Why wait for concrete to get hard? This easy-to-control tool is designed to start finishing on wet concrete, by using extension poles from outside the formed area, allowing the finisher to stay ahead of the curing process and establish an extremely flat surface. Ideal for decorative and special textures. No wiping out knee-board marks and footprints. ForConstructionPros.com/10079459

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

Power Pole Finisher

Extension Poles

34”

0-70

N/A

Handle Options

(Walk Behind Only)

N/A

Engine HP

Fuel Type

25 cc

Gas

F36 and F46 Walk-behind 5 MBW Power Trowels These 36- and 46-in. walk-behind power trowels feature heavy bearings, output shafts, gears, spiders and blade arms. • •

Longer handles provide greater leverage, are adjustable to fit the operator more comfortably and absorb trowel torque Balanced for performance and reduced operator fatigue

ForConstructionPros.com/12169700

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

F36

Walk-Behind

GX160 = 183 lbs., GX270 = 209 lbs.

35.5”

70-135

Mechanical/ Hydraulic

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

F46

Walk-Behind

GX270 = 246 lbs., GX390 = 260 lbs., GX390 High Speed = 267 lbs.

46”

70-135 rpm, High Speed 35180 rpm

Mechanical/ Hydraulic

Handle Options

(Walk Behind Only)

Low Vibration or Constant Force Pitch

Handle Options

(Walk Behind Only)

Low Vibration or Constant Force Pitch

Engine HP

Fuel Type

GX160 or GX270

Gas

Engine HP

Fuel Type

GX270, GX390, GX390 High Speed

Gas

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SPECIFICATION GUIDE: POWER TROWEL

6 MQ Whiteman STX6H

The new MQ Whiteman STX6H continues to raise the bar for all hydraulic ride-on power trowels. From the 70 HP Hatz Tier 4 Final turbo diesel engine to the Patented Power Management system, this new 10’ rider will handle every finishing need today’s contractor can encounter while on the job. Features include Cruise Control, LED lighting, SmartPitch, and a 12 volt outlet and drink holder for charging your electronic devices and operator convenience. ForConstructionPros.com/12169702

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

STX6H

Ride-On

2,544

117”

10-130

6 per rotor

Proportional Hydraulic

Handle Options

(Walk Behind Only)

N/A

Engine HP

Fuel Type

70 Turbo Diesel

Diesel

Engine HP

Fuel Type

Gas

7 New Engine Choice for Wacker Neuson CRT 48-PS Series

Concrete contractors can now choose between two gasoline engine options on Wacker Neuson’s 48-in. power steer (CRT 48-PS series) ride-on trowel product line. A new model, CRT 48-57K-PS, is powered by a 57-hp liquid cooled Kubota gasoline engine. It joins the 35-hp Vanguard air-cooled engine powered model, the CRT 48-35V-PS. The two models offer concrete contractors the ability to choose the power source that best fits their needs plus get all the benefits of Wacker Neuson’s patented two mode steering system and other high performance features. ForConstructionPros.com/12040035

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

CRT 48-57K-PS

Ride-On

1,500

48”

25-165

Power Steer

Handle Options

(Walk Behind Only)

N/A

POWER TROWELS WALK-BEHIND

W I N C H E S

Y INDUSTR RUCTION ST N O C THE HES FOR TY WINC SPECIAL

• Patent pending Low Vibration handle is multi axis shock mounted to reduce operator fatigue • Tool free height adjustable operator handle • ISO safety standard low guard ring allows easy cleaning and blade changes • Standard edger for close finishing • 36” or 46”

BLOOM MANUFACTURING, INC. Custom Engineered Solutions Since 1910 Independence, IA 50644, USA | bloommfg.com P: 319-827-1139 | 800-394-1139 | F: 319-827-1140

MBW, INC.

Slinger, Wisconsin

WWW.MBW.COM

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8 Packer Brothers Edger Trowel PB24

Packer Brothers Edger Trowel PB24 features: Centi-safety (Dead Man Switch) • Screw control adjustment for precise blade adjustment • Spider plate assembly is precision machined for total balance compensation • Guard rail edging feature for trowelling closer to walls up to 1/4” • Honda 5.5hp GX160 •

ForConstructionPros.com/ 12309269

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

E4dger Trowel PB

Walk-Behind

119

24”

N/A

Handle Options

(Walk Behind Only)

N/A

Engine HP

Fuel Type

Honda

Gas or Electric

9 Chicago Pneumatic STG244 TP Trowel

The Chicago Pneumatic STG244 has a 24-in. blade diameter and is CP’s edger in their trowel lineup. This includes user-friendly features and focuses on providing maximum safety for the operator. All versions of the CP trowel line feature QuickStop for safety, foldable low-vibration handles and a maintenance stand. With QuickStop, the blade rotation stops immediately with a zero-degree handle spin. The STG244 features a Honda GX 3.5 HP engine and has an operating weight of 132 pounds. ForConstructionPros.com/12307800 Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

Chicago Pneumatic STG244 TP Trowel

Walk-Behind

132

24”

40-115

N/A

Handle Options

(Walk Behind Only)

Foldable, adjustable

Engine HP

Fuel Type

Honda GX 120, 4 stroke 3.5 HP

N/A

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SPECIFICATION GUIDE: POWER TROWEL

10 Dura Manufacturing Trowels

This top quality power trowel is available in four configurations. You choose 36-in. or 46-in. diameter and standard blade pitch or a patented “Rapid Pitch” is available in both sizes. One of the best values in the world of Power Trowels. ForConstructionPros.com/12309244

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

DM24 Edger Trowel

N/A

119

N/A

65-130

N/A

Handle Options

(Walk Behind Only)

N/A

Engine HP

Fuel Type

Honda GX 160

N/A

11 RhinO-Tuff Power Trowels

All models come with Standard Twist Pitch Handle (SPH) but are available (and recommended) with the Rapid Pitch blade pitching system. It’s weight counter-balanced with infinite blade pitch adjustment from flat to maximum pitch. Maximize operator comfort with RhinO-Tuff’s revolutionary “vibration dampening” adjustable handle that minimizes the vibration transmitted to the operator thereby reducing the risk of operator repetitive injuries. The uniquely designed, fully adjustable handle increases running time up to 4.4 hours per day without exceeding ISO standards. ForConstructionPros.com/12307811 Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

R36H5-S

Walk-Behind

194

36”

65-130

N/A

Handle Options

(Walk Behind Only)

Standard Pitch

Engine HP

Fuel Type

GX160 Honda

N/A

COMPOSITE REBAR

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32 Concrete Contractor | March 2017 | www.forconstructionpros.com/concrete

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12 Master F30 Direct Drive Trowel Master F30 Direct Drive Trowel Direct Drive Means: • • • •

Low center of gravity No belt to adjust Less wobble and side torque Increased power to gearbox and spider

Longer blade life Only direct-drive trowel in the industry with a fully enclosed blade-pitch mechanism

• •

Electric deadman switch for safety Heavy-duty gearbox standard

• •

ForConstructionPros.com/12309253

Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

F30 Direct Drive Trowel

Walk-Behind

140

32.5”

60-120

N/A

Handle Options

(Walk Behind Only)

N/A

Engine HP

Fuel Type

Honda

N/A

13 Toro PT-36PP and PT-46PP Power Trowels

Toro power trowels feature contoured adjustable handles and a rotating stabilizing ring for precise handling that will deliver a smooth concrete finish. There are four models to choose from and each comes equipped with a Honda engine. The Toro Dyna-Clutch safety feature is incorporated into each unit and will stop the blade without shutting down the engine. The PT-36PP (pictured) and PT-46PP feature Toro’s patented Pro-Pitch blade adjustment system that provides smooth, quick pitch changes to ensure blades are at the optimal angle for a perfect finish. ForConstructionPros.com/10879819 Model

Walk Behind or Ride-On

Weight (lbs)

Troweling Diameter

Rotor RPM

# of Blades

Steering: Mechanical/ Hydraulic

PT-36 Power Trowel

Walk-Behind

219

36”

50-130

Mechanical

Handle Options

(Walk Behind Only)

Adjustable

Engine HP

Fuel Type

4.8

Gas

CORE DRILL & RIG SYSTEM

European Made! Top Qua lity! 3-Speed performance gea ring LED Motor overload prot ection Data retrieval software

800-850-2044 | Lackmond.com |

www.forconstructionpros.com/concrete | March 2017 | Concrete Contractor 33

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PRODUCT FOCUS

By Greg Udelhofen

Concrete Repair Keeps Customer in the

COLD The damaged threshold area has been removed to allow for a permanent repair.

Repairing an entrance threshold to a cold storage facility doesn’t have to be a disruptive experience.

t’s not always easy to convince customers that a concrete repair product will be the last solution needed to fix a crack, joint or spall in a commercial or industrial application, because most expect a predictive failure of any product used in a harsh environment. That doesn’t seem to be the case for Roadware’s 10 Minute Concrete Mender. Richard King II, vice president of sales and partner at Roadware Incorporated, pointed to the success a distributor/contractor has experienced repairing damaged cold storage thresholds, where forklift operators beat a path in and out of the subzero environment. “On one side of the threshold the temperature can be 40-50 degrees F,

while on the other side the temperature is minus 20 F or lower depending on the operation,” King notes. “Pro’s Choice Concrete Products LLC of Platte, Mo., has been repairing concrete surfaces in cold storage facilities for the past 20 years, and recommending and installing the 10 Minute Concrete Mender has been a relatively easy proposition when considering the standard epoxy solution. “We’ve been working with Pro’s Choice Concrete to educate customers of the advantages and reliability of our product,” King says. “Everyone uses epoxy to repair concrete in a cold storage facility and it fails.” Why? As King notes, to install an epoxy patch, you first have to empty the storage area in order to bring the temperature up to a minimum 40 F. Having to temporarily move the contents from a cold storage area to a reefer is in itself a major inconvenience. But going through the time and expense to move the valuable contents only to know the repair will eventually fail and have to be done again is frustrating and completely avoidable.

“It’s simple science. When you raise the temperature (of the cold storage area) to repair the failed concrete area, the concrete expands,” King states. “When you lower the temperature back down to minus 20 or colder, there will be contraction (shrinkage) of the concrete and the epoxy repair will fail. The reason 10 Minute Concrete Mender provides a long-term, even permanent repair is because the viscous nature of the liquid repair allows it to penetrate deeply into the structure of the concrete to form a “Microdowel” bonding to the solid substrate of a concrete slab. Granted it takes longer for the repair to cure in a cold environment (optimal curing temperature for the product is 70 F); however, it is not exposed to the expansion and contraction forces that occur when raising and lowering the temperature of the treated area. In a flash freezer application, King adds, where the temperature in the facility was minus 50 F, it did take three to four hours for the repair to cure, but there was no disruption to the operation and the contents of the facility did not have to be removed. “Unless you’re working in a cold storage facility, it’s difficult to understand how frustrating it is to maneuver over damaged concrete with either a forklift or pull cart,” King says. “And contractors are fed up trying to use other repair products and solutions that eventually fail.”

PLATTE REPAIR For Bob Kobush, the contractor owner of Pro’s Choice Concrete who repaired the damaged cold storage threshold, recommending, installing

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and training others how to install the 10 Minute Concrete Mender has become his new mantra. Whether it’s a customer who self-performs building maintenance or another contractor looking for the right solution, Kobush is confident he can deliver a permanent solution. To repair the threshold, he saw cut an 8 to 10-in. wide by 8 to 10-ft. long section and removed all material to a one-foot depth. In a typical threshold epoxy fix, the damaged area would be removed and replaced by a 4 by 4-ft. timber, covered with dense foam sheeting, which would then be covered with epoxy. Once the temperature in the cold storage is lowered to minus 20, the epoxy would snap. The repair Pro’s Choice installed was executed in layers using heavy aggregate to displace the Mender liquid deep into the surrounding concrete slab. The surface tension of the liquid solution is so low that it’s attracted to the rock content of the surrounding slab. In subsequent layers of the repair, more aggregate and a high-grade of sandblasting sand were used to expand and thicken the liquid Mender. “We spent five years testing this product on all types of warehouse slab issues like cracks, spalls and failed joints, and we encouraged forklift drivers to drive over the repair as soon as it’s cured to prove that it would stand up to the rigorous environment of a warehouse operation,” King says. “And when it comes to cold storage facilities, finding a permanent repair that doesn’t disrupt the operation is critical because a cold storage facility is the most expensive space to operate of any warehouse facility.” The finished repair will soon be ready for forklift traffic in and out of the cold storage area.

WHAT MAKES ROADWARE 10 MINUTE CONCRETE MENDER DIFFERENT FROM OTHER CONCRETE REPAIR PRODUCTS? Roadware 10 Minute Concrete Mender™ is a twopart polyurethane that penetrates deep into concrete to make permanent repairs. Nearly thin as water, it actually injects itself into the matrix of the concrete and shores up the existing concrete as it Microdowels into the concrete. In just minutes after application, Concrete Mender™ cures to a tough 4500psi polymer concrete that transfers heavy loads throughout the repair area.

Cures in just 10 minutes at 70°F (21°C) • Works in freezers below -20°F (-28°C) • May be polished • Never gets brittle • Easily applied • Contains no epoxy or polyurea • Easy to mix • Nonflammable • Low V.O.C’s • Paintable • Coatable • Sandable • Meets USDA guidelines

Self-mixing at point of application. Use a standard 1:1 ratio 600ml cartridge application gun.

Needle tip mixes are available for precise application. Choose from 14, 15 or 18 gauge.

Available in one gallon containers, two-gallon kits for larger application. Simply add sand and mix by hand. Also available in 10-gallon kits.

Extend with sand. One gallon of Concrete Mender™ makes about 2.2 gallons of repair material when combined with 2 parts silica sand. Twice the yield of epoxy or polyurea.

Repair concrete at working freezer temperatures below -20°F (-28°C).

Accepts polishing or most coating systems in about 10 minutes at 70°F (21°C)

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PRODUCT FOCUS Mortar Mix Plus Multipurpose Repair Material The high-performance, rapid-hardening Rapid Set MORTAR MIX PLUS (MMP) is a true multipurpose repair material. The specialty blend of Rapid Set hydraulic cement, advanced additives and quality aggregates is polymer-modified to strengthen adhesion and ensure there is ample working time when using this fast-setting material in vertical and overhead applications. In addition, MMP is durable in wet environments, making it especially suited for marine applications. • Formulated with an air-entraining admixture for freeze-thaw durability and an integral corrosion inhibitor to increase protection of embedded reinforcement • Non-metallic, with no chlorides added • Can be used for general and structural concrete repair, construction of pavements, underlayments, floors, formed concrete and more • Low shrinkage and fast strength gain. It sets quickly and reaches 2,000 psi (13.8 MPa) in as little as 1 ½ hours and 3,500 psi (24.1 MPa) in three hours. After 24 hours, it achieves a compressive strength of 5,000 psi (34.5 MPa). • MMP also reduces a project’s carbon footprint and lowers the environmental impact ForConstructionPros.com/12295893

Versaflex Quick Mender X.O. - A New and Improved Concrete Repair Polymer Quick Mender X.O. is a minimal odor system, specially formulated for interior and confined spaces; applied at a 1:1 mix ratio and may be applied with a steel bladed squeegee, ¼” nap roller, or brush. Quick Mender X.O. is available in 68 standard colors direct from the factory in easy-to-use 600ml cartridge sets, two quart kits, two gallon kits, 10 gallon kits and 110 gallon kits.

QUIKRETE Polymer Modified Structural Repair A polymer-modified, rapid-hardening, highstrengthen material, QUIKRETE Polymer Modified Structural Repair is designed for partial-depth repairs in vertical and horizontal surfaces from feathered edge to eight inches thick.

It can also be extended with gravel for fulldepth repair more than four inches • QUIKRETE Polymer Modified Structural Repair, which can be shaped to match the surrounding surfaces, is available in 20-pound pails for approximately $13 ForConstructionPros.com/12296779 •

Advantages Minimal Odor & VOC’s Low Viscosity in neat configuration will penetrate concrete for permanent bond • Fast return to service in 30 minutes • Can cure in -25°F. Cure time extended at lower temps. • Mix with dry industrial quartz to produce a durable polymer concrete • May be mixed with polishing dust, Portland cement, silica flour, fumed silica, and cabosil • Self-leveling • Good chemical resistance ForConstructionPros.com/12309277www • •

Metzger/McGuire's Edge-Pro 80 Edge-Pro 80 is Metzger/McGuire's newest addition to its line of semi-rigid concrete floor joint fillers. Edge-Pro 80 is a revolutionary new polyurea formula designed specifically to meet the challenges created by fast track construction schedules. The product is moisture tolerant and finishes flusher than most polyurea fillers used in stained and polished retail concrete floors today. • Packaged in both 600 ml dual cartridge convenience kits and 10 gallon kits. • Available in 13 standard colors. • The product can be pre-tinted or can be tinted in the field through use of a ColorFast color pack. ForConstructionPros.com/12252525

Rapid Flex CJ from SpecChem Rapid Flex CJ is a 100% solids, two component, UV resistant, semi-rigid, rapid curing, polyurea for filling control and construction joints in industrial concrete floors. Rapid Flex CJ allows for joints to be shaved quickly for fast turnaround. Rapid Flex CJ has been designed for use in compliance with ACI 302, section 4.10 recommendations for joint fillers used in saw cut/control joints with a Shore A Durometer of 85. Rapid Flex CJ can also be used for the repair of damaged or spalled joint nosing and cracks. ForConstructionPros.com/12258796

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Rapid Pavement Surface Repair Materials Five Star Rapid Surface Repair products ensure that all traffic can return to full-speed levels in just minutes. Rapid Surface Repair is a range of five unique products offering easy application techniques that result in a durable new surface ready to handle the fastest-moving, heaviest of traffic conditions on any and all roadways. • All Five Star Rapid Surface Repair Products offer fast repair and cure • They bond without primer to concrete, asphalt, steel or wood, thus saving labor time and expense • Additionally, Rapid Surface Repair Products seal and protect, prohibiting further corrosion of reinforcing steel • Extremely safe to use, as they emit no toxic fumes during application ForConstructionPros.com/12296161

Match Patch Pro FC Fast Cure Match Patch Pro FC Fast Cure concrete crack and spall repair system is specifically designed to aesthetically mimic existing concrete floors, while providing performance and abrasion resistance required. • On site color matching technique • Cure for polish in two hours • Accepts concrete dyes • Densifies with reactive silicates • Can be matched to concrete of any age close to perfection • Does not shrink or crack • Fast chemical resistant grouting system that impregnates the concrete fills and blends in the pin holes/imperfections such as spider cracking ForConstructionPros.com/12307056

Prosoco Consolideck Grind-N-Fill Consolideck Grind-N-Fill is a liquid crack and gap filler that takes a waste product – concrete dust from grinding – and repurposes it into something useful. By spraying and spreading Grind-N-Fill in front of a grinder and then grinding over it, the dust mixes with the product to create a slurry-like liquid to fill pinholes, micro-cracks and other blemishes in the floor. It then dries as hard as the concrete to create a smoother, more monolithic surface. • Grind-N-Fill makes floors easier to polish and maintain. • It can also expedite the job because it eliminates the need for an electric vacuum. ForConstructionPros.com/12306412

Thermal-Chem BarPatch 803 Thermal-Chem BarPatch 803 is a two-component, epoxy system designed to repair damage to coated rebar. Specifically designed to repair epoxy coated rebar damage (“nicks and dings”) incurred during shipping, handling, and fabricating. It covers and adheres to the sheared (knife sharp) cut ends of epoxy coated steel rebar and provides touch-up repairs for epoxy coated mechanical splice couplers. • Complies with all of the requirements of ASTM A775 (standard specification for epoxy coated steel rebar) • Available in convenient, easy to use 1.5 quart, 1.5 gallon, and 3 gallon kits ForConstructionPros. com/12224230

BECOME A DISTRIBUTOR AND STOP TROUBLESHOOTING SEALERS!

s t a m psh i e l d Provides stain protection by penetrating and chemically reacting with the natural materials found in concrete and stone.

For concrete, pavers and natural stone Permanent part of the surface Will not chip or peel Will not bubble or

turn white “After 30 years of trying, Trinic’s StampShield put an end to my sealer callbacks. When a customer calls now, it is to thank me for a job well Robbie Bauman, Bauman Brothers Concrete, done.” - 30 years in trade

gf r c

40 Grossett Drive, Suite 200, Kirkwood, NY 13795 1 (800) 475-1975 (607) 775-1948 www.trinic.us @trinicllc

www.forconstructionpros.com/concrete | March 2017 | Concrete Contractor 37

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FOUNDATION Q&A

By James R. Baty II

The Risk of NOT KNOWING This column presents a recent member inquiry on the nature of OSHA Fall Protection regulation. Through the interaction, we discovered a gap that exists between experience with fall protection and interpretation of the current regulation.

uestion: Yesterday, an OSHA inspector witnessed two of our crew members standing atop the formwork, while finishing a pour. The first worker was floating the wall and the second worker was installing anchor bolts. Both of these are standard procedures for us and the workers are trained and confident working from those levels. The inspector requested a meeting with an executive from the company. Today, when I met with the inspector, he suggested our company may be in violation of OSHA’s fall protection regulation for residential construction. I informed the inspector that our company utilizes an Alternative Fall Protection Plan, and this plan has proven to be safe and effective over the course of many years. He requested a copy of the plan, which he will submit to his superiors for review and wants

to interview our workers for their knowledge of the plan. I’m concerned that our plan, effective as it is, may not meet the OSHA requirements.

NSWER: Unfortunately, today this remains a common position found throughout the concrete foundation industry. Your situation exists due to a combination of factors including: • Lack of thorough understanding of OSHA for the nature of your business • Decades of experience in the industry where alternate fall protection was approved by OSHA for residential construction • Limited technological development of fall protection methods for the specific task of residential concrete foundation construction • Reality that the work you continue to do hasn’t changed beyond slight increases in average working height, still most commonly eight to 10 feet Today, contractors spend just as much time training and protecting their workforce through knowledge and experience as they have always provided. Protection of the workforce remains a top priority for the residential foundation company. What has been missed, however, are the changes in regulation that now require documentation of the decisions you make for fall protection systems and solutions and evidence of such application to each unique project or condition. In other words, OSHA wants to see the work you have done to take every aspect of fall protection safety into account and

Figure 1: OSHA’s website for Fall Protection in Residential Construction provides the complete set of regulations. Photo Credit: Concrete Foundations Association

understand the solutions you implement fully for compliance with the complete set of regulations. OSHA regulates in 29 CFR 1926.501 that an employer must provide fall protection. The title of this part of the Safety and Health Regulations for Construction is Duty to have fall protection. As an employer, it is your responsibility to know what constitutes the available fall protection systems and methods that are feasible for your job sites and develop a plan for implementing them. This regulations states that any worker on a walking or working surface 6 feet or more above the ground plane with an unprotected edge shall be protected by a guardrail, safety net or personal fall arrest system. Further in this section, however, residential construction is specifically addressed: 1926.501(b)(13) – "Residential construction." Each employee engaged in residential construction activities 6 feet (1.8 m) or more above lower levels shall be protected by guardrail systems, safety net system, or personal fall arrest system unless

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another provision in paragraph (b) of this section provides for an alternative fall protection measure. Exception: When the employer can demonstrate that it is infeasible or creates a greater hazard to use these systems, the employer shall develop and implement a fall protection plan which meets the requirements of paragraph (k) of 1926.502. Since there is currently no commercially available guardrail, safety net or personal fall arrest system that has been engineered to work with removable concrete forms, utilization of these systems is technologically infeasible and forces poured wall contractors to utilize other measures to protect their workforce. However, these contractors may or may not be OSHA compliant, depending on whether they’ve strictly complied with the prescriptive requirements of 1926.502(k). Employers must take caution in using the terms infeasible and greater hazard. These are the key terms that must be accounted for in your research to justify the implementation of a fall protection plan. It is the employer that bares the full burden of establishing the appropriateness of implementing such a plan rather than one of the three noted systems. Here, OSHA set the acceptance of an “alternate fall protection plan” as described in subpart M in lieu of compliance using fall protection systems without any burden of responsibility for proving infeasibility or greater hazard. In 1998, STD 3.1 was replaced by STD 3-0.1A that augmented this position with specific requirements that must be addressed by the alternate fall protection, including monitoring and training. OSHA rescinded this position in 2010 under the presumption that commercially available systems had advanced in the industry to sufficiently support fall protection system implementation for all residential construction. Many contractors claim that instead of using fall protection they use an “alternate fall protection plan”. It is important to note that under the current direction, an alternate fall protection plan is a form of fall protection, but one that requires the use of

knowledge to demonstrate both technological infeasibility and greater hazard to the worker for each procedure. Your plan must discuss the extent of consideration for the use of “scaffolds, ladders, or vehicle mounted work platforms” to “provide a safer working surface and thereby reduce the hazard of falling.” When these methods of providing alternative working surfaces are exhausted through the demonstration of technological infeasibility and/ or greater hazard, the employer then classifies work surfaces as controlled access zones in conformance with 1926.502(g) and implement safety monitoring systems in conformance with 1926.502 (h). 1926.502(k) “Fall protection plan” is an option for only three types of work; leading edge, precast and residential construction. As you analyze the work you are doing, both leading edge and residential construction are applicable and each implies looking at your plan from different perspectives. The person that develops the plan must be a “qualified person”. According to OSHA, this is defined as one who, by possession of a recognized degree, certificate, or professional standing, or who by extensive knowledge, training and experience, has successfully demonstrated his ability to solve or resolve problems relating to the subject matter, the work, or the project. From this point, the rest of the fall protection plan can be developed. There are many aspects of developing such a plan that you will need to consider. These include introduction, acceptance, training, certification, infeasibility for fall protection systems, use of a combination of methods, identification of a competent person for each project site, adaptability of the plan to specific site conditions or project details and much more. In the end, OSHA expects you to not only own the responsibility for keeping your residential foundation crews safe, they want you to be able to demonstrate and prove to them that you have control of the situation and your employees understand the plans they are following. This is

the method by which they can then understand that your company is actively implementing effective fall protection safety. The Concrete Foundations Association makes available a Fall Protection Plan Development Kit to its members covering all aspects of the regulations found throughout 1926.501 and 1926.502 as well as the history of the industry impact from these OSHA regulations. References: 1. Standards – 29 CFR, parts 1926.501, 1926.502 published by the Occupational Safety & Health Administration | www.osha.gov 2. Standards – STD 3.1, STD3.01A expired published by the Occupational Safety & Health Administration | www.osha.gov

Ed. Note: Jim Baty is the Executive Director of the CFA and can be reached at (866) 232-9255 or by email at jbaty@cfawalls.org.

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The Bonds in Diamond Grinding and Polishing The key to troubleshooting tooling problems is in understanding the bond. by Mike Orzechowski

he bond is one of the most important (but often overlooked) components of diamond tooling. The tools are often categorized into a select few groupings like hard, medium or soft metal-bond, hybrid/semi-metal bond, and wet or dry resin bond. In general there is not a good appreciation for the multitude of variations of the bond in each of those overly simplified category classifications. A simple root-cause-analysis of performance problems of a tool from jobsite to jobsite, or on different brand machines on the same jobsite often boil down to the bond (directly or indirectly). For many diamond tool makers the bond often represents a larger allocation of the research and development budget because there is an overabundance of variables that can be tweaked to make huge changes on the performance characteristics of the finished tool. Unfortunately the bond is usually the least understood part of the system and arguably the most important. The bond is an integral part of the complete system, and to understand the bond requires an understanding of how the other parts of the complete system

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influence the performance of the bond. The bond is not the only component or consideration for the design of a diamond tool. In addition to the quantity and quality of the diamonds in the tool and the bond used to hold them in place, it is important for the diamond tool maker to look at the complete system, a holistic approach, to include parameters like the machine, is the grinding performed wet or dry, and the slab hardness and abrasiveness. It is almost overwhelming to consider how many things can change from jobsite to jobsite or from slab to slab that can drastically impact the performance of the diamond tooling. Fortunately in a practical sense, with the same operator using one machine bidding similar jobs (pick one: residential, commercial or big box stores) and grinding the same way either with a dry vacuum or wet, then many times the list is drastically narrowed to basically just the parameters of the diamond tool and how it matches the â&#x20AC;&#x2DC;systemâ&#x20AC;&#x2122; they defined. Ideally they want to optimize the performance of the diamond tool for their system, but sometimes it is easier to tweak some part of their system to optimize it for the diamond tools available to them for the machine they are using. It is also very important to know about the different tooling for

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the occasional job that may be very different than the jobs they usually work on.

PAIRING THE DIAMONDS WITH THE BOND The bond holds the diamond crystals in the diamond tool for the abrasive grinding process of the diamond to the slab surface. Grinding is a mutually abrasive process of the tool and the slab surface but with diamonds being extremely hard with respect to the slab surface, the wear rate of the tool is significantly less than the slab surface. The size of the diamond crystal can dictate the grinding speed and effectiveness in penetrating non-abrasive coatings or sealers, and progressively smaller diamond crystal sizes can remove the scratches from the previous step. For the toolmaker, it is important to

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create a bond based on the quality of the diamond, the size of the diamond and the abrasiveness of the slab surface, so that the bond allows diamonds to wear, fracture to expose new sharp edges, as well as to release old diamonds (pullout). If the bond is softer than an optimum bond, the bond will wear away faster and can cause more diamonds to pullout before those diamonds can wear down or fracture, causing the life of the diamond tool to be very short. If the bond is harder than an optimum bond, the bond

will have an excess of diamonds that are rounded and worn out, without enough old diamonds being released and replaced with new diamonds and eventually the surface of the diamond tool will glaze over and lose its effectiveness as a grinding tool. It is interesting to note that the term ‘diamond’ is derived from an ancient Greek word for ‘Unbreakable’. However, not all diamonds are alike. The diamond in a tool is defined by three basic parameters: the quality, the size and the concentration. Sorting diamonds by quality is often misunderstood, these are not gem grade diamonds sorted by color, cut and clarity. The synthetic diamonds used in grinding tools are sorted and graded by the shape of the crystal Arrowhead TEQ Lok. Photo Credit: Diteq

and the impact strength using quantifiable metrics like a the toughness index (TI), thermal toughness index (TTI) or compressive fracture strength test (CFS). The diamonds are also sorted by physical size referred to as a mesh (or Grit) size (As the Grit size increases, the actual size of each diamond crystal decreases). The diamond concentration in the tool is a measurement of the total carat weight of the diamonds per a unit volume of the bonded tool (100 CON = 72 carats/cubic inch). Typically, diamond tool makers do not label the tools with the diamond quality or concentration. The design of the tool involves so many ingredients

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Storm Cup Wheel. Photo Credit: Diteq

to achieve very strategic design goals on specific machines, that knowing just a couple of the ingredients without understanding all the variables could confuse more than clarify how it impacts the tool performance.

Metal bonds are good for larger diamonds with diamond mesh sizes up to 400G (practically more likely around 200G). Resin bonded diamond tools have a much softer bond to allow the smaller diamonds to release more freely as the tool

BOND HARDNESS – SOFT / MEDIUM / HARD There is no universal hardness designation on diamond tooling, it is a relative scale. There is a big difference in the tooling used on a low horsepower lightweight class of machines versus a high horsepower heavy class machine. So for a medium bond designed for normal grinding conditions on one class machine would be completely different on a different class machine. Frequently the diamond tool makers might mark the low HP lightweight machine ‘medium’ bond tooling as a ‘general purpose’ bond to help avoid confusion.

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is used (up to 6500G buff pads but practically more likely 3000G). Resin bond diamond tools can be very complicated to fully understand, but for discussion purposes it can be simplified to wet or dry resin tools. The big difference is mainly in the extreme temperatures in dry grinding can melt the resins or polymers or sometimes soften them enough so the diamonds in the bond can wiggle enough to create a socket which leads to diamond pullout. There are many techniques for the diamond tool maker in selecting a resin and using different types of coated diamonds or admixtures in the resin to create more aggressive and longer life tooling. These lead to group of diamond tools called transitionals (sometimes also referred to as hybrids or semi-metals.)

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The data collected using a profilometer to meet the requirements of CSDA ST115 standard have been shown to also provide measurements for the performance of the diamond tooling. The grit size measures the physical size of the diamonds in the tool and do not reflect the strength of the bond which allows the diamond to protrude from the tool as a grinding point that creates a measureable scratch pattern in the slab surface.

DRESSING THE DIAMOND TOOL Many times when the diamond tools are made, the top surface of the diamonds are covered with the bond. It is important to break-in (also referred to as dressing) the diamond tools to expose a layer of diamonds. Some resin tools burn a fine waffle pattern in the top surface of the tool to speed up the break-in process. Many of the metal bonded tools are dressed at the factory by the diamond tool maker. It is important to certain that new resin bond tools are properly broken-in before making a final production run.

OPERATOR CONTROL OF THE DIAMOND TOOL Some operators have elevated grinding and polishing concrete to very high competency levels, true craftsman at the art of polishing. It seems like they can feel the machine or hear the tooling scratching the floor and know the progress of the slab refinement. These true craftsman might have machine and diamond tooling preferences but can polish a floor using almost any polishing machine or tooling (within reason) by operator technique. This is where training and experience is so important in learning valuable skills. Diamond tools are designed for specific slab or slab conditions

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in a specific class of machines based on the weight pressure forces on the diamonds (not from the overall weight of the machine but the head pressure on the tooling) and the speed of the diamonds (it becomes very complicated in calculating the speed of some planetary machines). Because of these speeds and pressures are driven by a class of machines, sometimes a tool that performs well on one class machine might not do well on a different class. It is not that it is a bad tool, but rather it is not the right tool for the machine and application. Increasing the speed of the diamonds will act like the bond of the diamond tool is harder. For very abrasive slab surfaces a harder bond will extend the life of the tool. Decreasing the speed of the diamonds will act like the bond of the diamond tool is softer. Many stones in heavy exposed aggregate are not very abrasive and require a softer bond to prevent them from glazing.

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Hard or critically hard concrete surfaces would also require a softer bond to prevent glazing. Grinding dry can create higher temperatures which can damage the diamond tooling. Using higher airflow vacuums (high CFM) can sometimes help keep the tools cooler. Wet grinding is a great way to keep the diamonds cool but it is often misunderstood. If the volume of water is high enough to keep the slurry generated somewhat translucent then the water will act as a lubricant. If the slurry generated is a thicker paste, the slurry will act as an abrasive to help keep the diamonds open and new diamonds exposed by wearing away the bond. True craftsman generally have a good understanding of the bond. Often times they do not always effectively articulate why something is happening, but they seem to know instinctively what they need to do to optimize the performance of the tools they have. Do not be afraid to try something new. Use the knowledge in the performance of existing tooling and techniques as metric to compare some new products or techniques to improve and grow.

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POLISHED CONCRETE

MAINTENANCE: A Trip Through the Past and A Look at the Future

What is the next generation of maintenance products for polished concrete floors and where can contractors find them? by David Stephenson

he mechanical process of refining and smoothing the concrete does create a finish that does not need to be maintained in the same manner as traditional flooring options at that time. There is no daily buffing needed. No waxing and stripping is required.

So, in that sense the floors were no maintenance. But what was discovered quickly is that the concrete can and did scratch ever so slightly when sand particles are pressed into the floor and slid across the surface. This means that foot traffic, cart traffic and any other process that created an abrasive action would wear the floors down slowly. These small micro-scratches build up over time and lower the smooth finish and therefore the overall shine of the floor. With this new-found knowledge, the manufacturers that were the most invested in the polished concrete market stared scrambling to find a floor cleaner or maintenance system that would help solve the scratching situation and extend the life of the floors. The first processes put forth

were to sweep regularly and clean the floors with water only. Then we started saying â&#x20AC;&#x153;add a little bit of soft soap, like dish washing soap to the scrubber water.â&#x20AC;? Next came the first polished concrete cleaners. These were simple neutral cleaners that would lift the dirt allowing for easier scrubbing. As time went along and the information and feedback came in, the products continued to change. Manufacturers had cleaners developed with a bit of densifier in them. Theoretically these cleaners would continually harden the surface as they made it denser and harder which would make it more durable and resistant to micro-scratching.

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chemical manufacturing companies and as private label products for grinding machinery manufacturers. These construction industry manufacturers developed maintenance systems as a way of protecting their core products. Today, most of these types of products are sold directly to contractors and customers, or sold through construction supply houses. This makes polished concrete maintenance difficult to sustain. The janitorial contractors that traditionally maintain floors already have good relationships built with their janitorial distribution companies. They want to buy from their regular suppliers. The only issue is that their regular suppliers do not make products that are a good fit for polished concrete. This leads to “best guess” substitutions of cleaning products. These substitutions typically do more harm than good. Cleaners that are standard and

fine for VCT or Terrazzo floors with a sealer as a protectant and a disposable wax as a living surface do not do well for concrete floors. I field calls daily from store managers, janitorial contractors or retail regional managers discussing problems on existing projects. I find problems that start with “the color is coming off on our floors” usually means that the cleaner being used has a solvent in it which strangely enough affects solvent based dye color. Problems that start with “My floor is losing its shine much faster than I expected” typically means that the cleaner they are using has an acid component that is having a chemical reaction with the concrete and eats the surface. This results in pitting, which lowers the shine. As a side note, I did have one customer though that was using an approved polished concrete cleaner but had no shine less than a year after opening. I was having a hard time understanding why the floor was losing its gloss

in all the main isle ways only. Even the color was coming out in specific patterns and areas. We talked several times with all the parties about the scrubbing process and chemicals and pads that were being used and it all seemed in order. After showing up on site at 2:00 in the morning for a surprise visit, I found the issue. The maintenance program stated that the floor should be burnished two to four times per year with a diamond impregnated burnishing pad. The store manager thought “If burnishing four times a year is good, then burnishing nightly would be much better”, so that’s what they were doing. Burnishing nightly with a 400grit pad for a year. This resulted in a slow sanding of the surface only in the main walk ways where the burnisher was running. As you can see there are a lot of possible ways the simple process of polished concrete maintenance can be mismanaged or messed up.

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WHERE THE INDUSTRY IS HEADED As polished concrete continues to gain momentum, the large janitorial manufacturing companies will start working to develop processes, chemicals and programs to address this large market segment. I believe that the janitorial giants have not wanted to get into polished concrete

maintenance because the margins and volume are not as large as other flooring types. This mindset is changing though because the sheer volume of polished concrete floors being completed annually makes up a major and growing segment of the overall flooring market. Over the next few years I believe

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every major janitorial supplier will carry products specifically made to address the polished concrete market. I see two ways that the market for maintenance systems can go. Alternate flooring types are lucrative because the sealer or wax is replaced regularly. This is at a large cost to the owner, but the floors always look good. Most of the damage that occurs is held at the surface and only affects the disposable sealer. I know of one large manufacturer that currently sells a thin topical sealer system that needs to be replaced several times a year. I could see the manufacturers pushing to go this direction because it would mean higher revenue as more product is used. I think this approach will slowly collapse the polished concrete market. My thought process behind the statement of a slow collapse is that polished concrete is an attractive floor because of the look, but there are always flaws and imperfections in the concrete slab. The true benefit is the lower maintenance cost. If the market goes to a disposable sealer regularly applied, it will creep the maintenance costs up. Currently, using a good maintenance program with the best available polished concrete cleaners and regular burnishing, a customer will spend less than 75 cents per foot per year to maintain their floor. This investment will keep the floor serviceable for 10 years or longer. Compare that to VCT which has an average maintenance cost of $1.50-$2.00 per foot per year for scrubbing, buffing, stripping and waxing. VCT has an average life of 10 years or less and then it needs to be completely removed and re-installed. The average cost for removal and replacement of VCT is $4.50 per foot. Compare to polished concrete at a refurbish cost of $1.25-$1.50 per foot. The concrete never needs to be removed so the refurbish is less invasive and much quicker. If the maintenance cost of polished

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concrete creeps up towards the $1.00-1.25 per foot per year range, I do not think most retailers or owners would be as willing to deal with the inherent defects of concrete for the minor savings that are achieved. This will cause a decrease in the projects specified and a slow collapse of the industry. The other route that can be taken is truly â&#x20AC;&#x153;maintainingâ&#x20AC;? the existing finish. This involves performing mechanical treatments to the floor to keep the polish at or near the level of shine that was provided at the time of installation. There is one system like this that has hit the market recently by one of the larger janitorial product manufacturers. I am very excited by this mechanical path to successful maintenance as I see it continuing to expand the

industry. The fundamental value of polished concrete is mechanically profiling the concrete surface to be smooth and polished. I see this type of mechanical maintenance program as boosting this core benefit daily while working to address the weaknesses of a flooring system without a sealer or sacrificial finish. Mechanically handling the maintenance daily removes the effects of micro-scratches that are created by the sanding action of the soil that we talked about at the beginning of this article. I see this as a fantastic solution, especially when a mechanical system is used with a good cleaner where densifier and stain protection are regularly applied to the floors. Based on the data that I have looked at this type of floor maintenance program will hold

on to the substantial cost benefits of polished concrete flooring while addressing gloss levels and the periodic staining that occurs through routine usage. I see this type of system being especially valuable in the food service and grocery sectors. The future of polished concrete as a flooring process is closely tied to the ability to sustain the look and durability of the finish. Maintenance can either help or rapidly hurt the overall look of the finish. As polished concrete continues to grow and become the flooring of choice, large manufacturers will start to court the industry with systems developed specifically to address the concerns discussed here. I am excited to see the next chapter in maintenance.

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THE LAST PLACEMENT: BACK TO BASICS

By Brad Humphrey

The Honor in

LEADING OTHERS Leading others is about the commitment the leader feels to be the best they can be

eading others is still an honorable profession. It embraces the reality that others depend on the leader’s insights, openness to accept other ideas and diligence to see each person be all that they can be as a worker. But in today’s market many contractors and construction leaders are finding a serious shortage of individuals who are open to and interested in taking that next step in their professional development, that of being a leader. Here are a few reasons why leading others is still an honor:

PROVIDES GROWTH FOR OTHERS

Effective leaders have always been focused on developing the “others” in reaching their potential. Such leaders are rare, but they sincerely believe in what a person can become, what they can still attain in their knowledge, their skills, and their love for their craft.

EXPANDS THE LEADER’S GROWTH

It was once noted that when General Dwight D. Eisenhower was made supreme commander of the world’s allies during World War II, that his growth to lead those whom he had leapfrogged over was just short of astounding. Briefly, General Eisenhower’s mission to lead others contributed greatly to his ability to

influence, temper and challenge other leaders. This growth perhaps contributed most to his becoming President of the United States of America a few years after the war ended. The construction leader who embraces their opportunity sincerely will also find that their own growth is stimulated by their search for better approaches, solutions and inspiration.

CONFRONTS A LEADER’S FEARS

Everyone deals with the anxiousness of feeling vulnerable, not feeling in control of their situation. Every leader has felt the fear of failure looming before a big decision is made or project is completed. Yet, it is this same confrontation that moves good leaders to great leaders. When a leader has developed themselves into a disciplined employee, one who views others with hope and interest, and who has learned the benefit to proper training and organization, that leader will then be more confident to confront those anxious opportunities with calm and steadiness. Such leaders confidently move to and through the impending situation.

INFLUENCES FAITH AND HOPE IN OTHERS

Most followers want to believe that their leader is looking out for them, fully aware of what lies ahead and seeks out the best processes, methods and resources to succeed in their tasks and projects. Until proven otherwise, a crew of workers, a project team or the employees in a department will develop a faith in their leader and a hope for the best resolution. The leader who wins the faith and hope

The opportunity to lead others represents the trust in the leader to make the right decision, influence the right behavior and secure the right building practices. Photo Credit: FreeDigitalPhotos.net

of their followers will achieve many things never before imagined.

REFLECTS A LEADER’S SELF-RESPECT

Great leaders have a healthy respect for themselves. They realize their strengths and have clarity of their weaknesses. They seek not to glorify themselves but rather seek to raise the talent and reputation of those whom they lead.

REPRESENTS A LEADER’S TRUST

For any construction leader, being given the opportunity to lead others represents the trust that their senior leaders have placed in the leader to make the right decision, influence the right behavior and secure the right building practices. Without the trust of the “higher ups” a leader feels isolated and alone. Embrace the opportunity of leading others. Embrace the honor and respect that should be part of your desire to see great results. Embrace seriously those processes, preferences and methods that your company has asked you to follow and uphold. And finally, embrace those whom are now in your charge and under your care and oversight. Here’s to being honorable in bringing honor to leading others! Brad Humphrey is President of Pinnacle Development Group, a consulting firm that specializes in the construction industry.

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