Concrete Contractor June/July 2017 by ForConstructionPros.com

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Going Out on a Limb is Easier than Building on a Cliff

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June/July 2017 | Issue 4, Volume 17

WHAT’S INSIDE Cover Photo Credit: Ekedal Concrete, Inc

Departments 4 Editor’s Letter 6 Challenging the System 10 Legal Matters

What’s Online

Cover Story 16 Going Out on a Limb is Easier than Building on a Cliff This feature connects you with the Concrete Foundation Association’s Grand Project of the Year, one of the many projects receiving recognition in the association’s 2017 Projects of the Year competition.

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

Features 12 Carbonation in Freshly Placed Slabs The reaction between cement paste and carbon dioxide in the air.

20 Special Report: OSHA Silica Rule: Are You Ready?

Ensuring an Urban Oasis Remains Watertight

Enforcing Crystalline Silica Standard in Construction Industry begins Sept. 23.

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26 Durable Epoxy Coatings Provide Endless Design Possibilities Concrete Designs Enterprises takes artistic approach with epoxy floor systems to build a successful decorative business in Louisville, Ky.

32 Equipment Specification Guides: Concrete Saws A compilation of technical information when choosing your next concrete saw.

36 Thermal Cracking

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Why it happens and how to control it.

www.forconstructionpros.com/concrete | June/July 2017 | Concrete Contractor 3

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EDITOR’S LETTER

PCA Releases Spring Forecast, and the Outlook looks positive Ryan Olson, Publisher/ Editorial Director

n May, the Portland Cement Association announced it expects U.S. cement consumption to reach 3.5% annual growth during the remainder of 2017 and 2018. The association is forecasting growth in the years ahead using conservative baseline estimate for factors such as infrastructure spending and tax reform. “While fiscal stimulus will boost cement consumption, there are other economic indicators that will temper growth,” Chief Economist Ed Sullivan says. Tax reform will have a key impact on cement consumption, as it drives consumer spending and confidence that play heavily with the housing sector, according to PCA. “The underlying fundamentals supporting economic growth are positive, though we’ll maintain a watch on how the U.S. government addresses possible inflation and immigration policy,” Sullivan says. “This confidence in stable, sustained growth in cement consumption is likely to be unchallenged through 2018.”

Facebook.com/ ConcreteContractor

Advisory Board

ROlson@ ACBusinessMedia.com (800) 538-5544

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

4 Concrete Contractor | June/July 2017 | www.forconstructionpros.com/concrete

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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 June/July 2017, Issue 4, Volume 17 One year subscription to nonqualified individuals: U.S. 1 year: $35, 2 years: $70. Canada & Mexico 1 year: $60, 2 years: $105. All other countries 1 year: $85, 2 years: $160 (payable in U.S. funds drawn on U.S. banks). Single copies available (prepaid only) $10.00 each (U.S., Canada & Mexico), $15.00 each (International). Canada Post PM40612608. Return Undeliverable Canadian Addresses to: Concrete Contractor, PO Box 25542, London, ON N6C 6B2.

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CHALLENGING THE SYSTEM

STIFF CONCRETES = STIFF BACKS Stiff concrete slumps (4 in. or less) lead to more worker injuries.

n the ongoing effort to improve jobsite safety, the effects of concrete properties on often unnoticed worker injuries have been largely ignored. The injuries can be grouped into one category: musculoskeletal disorder (MSD). This includes worker injuries to muscles, tendons, ligaments, nerves, joints and spinal discs. MSDs don’t get as much attention because they don’t cause instantaneous injury as with many trip-and-fall incidents, but instead develop gradually with time. They can, however, result in back pain, carpal tunnel syndrome in wrists and hands, tennis elbow, rotator cuff disorders in shoulders, and bursitis in knees and shoulders.1 These injuries are the single largest cause of medical expense and lost work time among workers in the U.S. and Canada. 2 A primary contributing factor to such injuries is shoveling, spreading, raking, and striking off stiff concrete by hand for concrete slabs on ground or for elevated slabs. In the March 2017 issue of Concrete Contractor, we advocated having the slump requirements determined not by specifications but by an agreement between the concrete producer and contractor. That’s because slump is not a reliable indicator of strength, as it was once thought to be. We said further that slump does affect the ease with which concrete can be transported, placed, and screeded. That’s one reason for letting the contractor decide the slump: Higher slumps result in greater productivity.

Reinforcing bars protruding from some slabs prevent the use of mechanical placement aids such as vibrating screeds. Photo Credit: Baker Concrete

But we can add another reason. Default specification values for slump, based on the old idea that stiffer mixtures result in higher quality concrete, actually result in a greater probability of MSDs.

MSD RISK FACTORS The risk factors for MSD can include forceful exertion, awkward positions, and repetitive motions, all of which are involved in shoveling, spreading, raking, and striking off concrete when slipform pavers, laser-guided vibrating screeds, bridge-deck pavers, or other such mechanical aids are not used. When building most of today’s large industrial floors or pavements, commercial floors, and bridge decks, mechanical aids are used, primarily to increase productivity and reduce costs. But there are still many concrete slabs placed with no mechanical aids because the use of such aids is prevented by accessibility, lack of maneuverability room on site, and obstacles created by

reinforcing bars or electrical and plumbing protrusions through slabs.3 On these placements, specified slumps of 4 in. or less increase the likelihood that workers will develop MSDs. This has been shown by both anecdotal information from workers and by experimental evidence.

ERGONOMICS RESEARCH SHOWS THE DANGERS Ergonomics can be defined as fitting the job or task to the worker, with the goal of reducing the risk of MSDs.4 In Australia, the Concrete Industry Association Queensland (CIAQ) established an industry working party. Workplace Health and Safety Queensland (WHSQ) was also represented on this industry working party. The working party’s purpose was to instigate an industry change from a default slump value of 3- to 4–in. for commercial flatwork. This was driven by industry concerns regarding the musculoskeletal injury risks

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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

associated with lower slump values. In July 2008 the Construction Industry Sector Standing Committee (ISSC) received a letter from the CIAQ seeking endorsement for pursuing this issue. The ISSC requested a WHSQ Principal Advisor on Ergonomics to assess the musculoskeletal injury risks associated with a 3-in-slump concrete in a commercial construction setting. The aim of the project was to gather information in relation to the commercial construction industry’s current use of a default concrete slump value of 3-in. during concreting activities and its impact on musculoskeletal injury

Repetitive motions involved in hand raking and screeding of concrete with slumps less than 4 in. are likely to cause musculoskeletal disorders in workers.

risks. Anecdotal information provided by workers and management in the concreting industry, WHSQ construction inspectors and industry representatives indicated that slumps of 3 in. contribute to the force required when performing the concreting tasks.3 This anecdotal information has been verified by testing.

ERGONOMIC TESTING RESULTS One article from a newsletter, Lifeline from the Laborers’ Health

and Safety Fund of North America (LHSFNA), 5 discussed the increased body stressing risks with lower slump values and provided a link to tip sheets6 specifically targeting concreting activities. The tip sheet on slump reported results of using an instrumented rake to measure the pull force needed to varying slumps. With a 1-in. slump, the mean force to pull material with the rake was 46 lb. In comparison, a 3-in. slump required an average of 27 lb, and a 6-in. slump required only 20 lb.7 Forces required to move concrete with a shovel have also been measured. In a study by the Canadian Infrastructure Health and Safety Association,8 shoveling forces at various slump levels were evaluated by having workers shovel concrete with a load cell attached to the lower portion of the shovel handle. Ten shoveling tasks were performed on concretes with slumps of 3-, 4-, 5-, and 6-in., with the forces represented by the averaged peak forces measured by the load cell. The results indicated that with concrete slumps less than 5-in., lifting forces can exceed 44 lb. and increase the risk of MSDs such as chronic lower-back and shoulder pain.

CONSEQUENCES OF MSDS The difficulty in recruiting and retaining workers in the concrete industry is at least partially attributable to a decrease in worker health and longevity as a result of MSDs. In addition, workers compensation claims related to the

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

long-term effects of MSDs increase cost. This cost increase is passed on to the owner of the structure being built. One step that specifiers can take to decrease costs is eliminating default specification requirements for slabs that often include a slump range of 3- to 5-in. or 4- to 6-in. Then let the contractor choose the slump based on the jobsite conditions that dictate the degree to which mechanical aids can be used. This is a win-win solution. Workers are less likely to develop debilitating injuries, contractor productivity increases, and building costs decrease.

References

1. Concrete Finishers Health & Safety Manual, Infrastructure Health and Safety Association, Mississauga, Ontario, Canada, 2016, p.7-1. 2. “Washington Ergonomic Project Addresses Concrete Construction,” https://www.lhsfna.org/index.cfm/lifelines/fall-2003/washington-ergonomics-project-addresses-concrete-construction/ Fall 2003. 3. “Concrete Slump Project Report,” Department of Justice and AttorneyGeneral, workplace Health and Safety Queensland, AU, July 2009, p. 11. 4. “Ergonomics in Construction,” Tool Box Tips, Washington University of St. Louis School of Medicine, 2014. 5. www.lhsfna.org/index.cfm?objectID=84B79A28-D56F-E6FA-964965E231 6BE729 6. www.lhsfna.org/files/slump_tipsheet_final. pdf 7. “Choose the Best Slump for the Job,” Tip Sheet developed by Build It Smart, Laborers’ Health and Safety Fund of North America, Laborers’ International Union of North Americas, AGC of Washington, University of Washington, Western Washington Cement Masons Training Center, and the Stewart Prezant Ergonomics Group. 8. Vi, Peter, “Effects of Slump Level on Shoveling Weight of Concrete,” Infrastructure Health and Safety Association, April 2016, 4 pp.

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LEGAL MATTERS

The Usual QUESTIONS

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.

Know when to set up a Performance Improvement Plan when an employee is not performing at expected levels.

he other day I got a call from an old friend, Bill. He runs a small business with about 40 employees. Bill is a good guy who generally knows what he can and cannot do lawfully, but he sometimes calls me to make sure he’s right. Bill told me he has a long time employee named Mark that he’s thinking about letting go. According to Bill, Mark is no longer able to do the work. I began asking Bill the usual questions. “What is Mark’s race?” “He’s white.” That pretty much eliminates any sort of race or color discrimination claim. Let’s see about the rest of Title VII. “Do you have any females that do what Mark does?” “No. He’s a field laborer in my concrete business.” That takes care of sex discrimination. “Do you know Mark’s religion?” “No, I don’t. I know he doesn’t go to my church.” “But, that isn’t a factor here, is it Bill?” “No.” Okay, that eliminates religious discrimination. “Do you know Mark’s national origin?” “I assume he’s American.” Then there is no national origin discrimination either. That clears any Title VII issues. Let’s look at other possible issues. “Is Mark disabled in any way?” “Not really. He’s just much slower than he used to be.” “Bill, do you perceive that this is due to a disability of any kind?”

“No, I think it is just age, but he just isn’t getting the work done.” Well if he does not claim a disability and you don’t perceive him as disabled, he doesn’t have an Americans with Disabilities Act claim. “How old is Mark?” “I think he’s about 45 years old.” Then he is covered by the Age Discrimination in Employment Act. This is probably the greatest risk for the concrete contractor as the workforce gradually ages. “Have you documented Mark’s inability to do the job?” “Not really. My crew leaders tell me that he’s just not cutting it. And on a couple of recent jobs we incurred overtime expenses that were caused by Mark’s slow performance – at least that’s what the crew leaders tell me.” “Does Mark have a problem with any particular crew leader?” “No, all of the crew leaders think Mark is the slowest worker and each tries to avoid having Mark on his crew.” “Have you had any discussions with Mark about his performance problems?” “No, I am just trying to be proactive and look out for my business.” Okay, we have a white Caucasian American who is over 40 with no apparent disabilities or religious affiliation and whose performance failings have not really been documented. I suggested that Bill put Mark on a “Performance Improvement Plan” with a defined goal and deadlines that they jointly discussed and agreed upon. This gives Bill the chance to document

Mark’s problems and may lead Mark to the conclusion that he can no longer do the work. Mark presents a situation that more and more concrete contractors will face as their workforce ages. Although some workers will get injured, you would like to minimize this. Still more workers will just slow down. As the business owner, you have to decide how much is enough and where to draw the line. In doing so, it is vital that you be consistent and fair. When you use a performance improvement plan, set realistic, attainable, measurable goals and deadlines. Follow-up is critical. If the worker is permitted to “skip” a deadline, you will lose the ability to effectively discipline and/or manage the worker’s performance. Documentation is also critical. You need to have some objective measurement of the decline in performance. Otherwise, you are open to liability for (usually) age discrimination. Essentially, the worker claims that you are eliminating workers over 40 years of age in favor of younger, stronger workers. If you cannot demonstrate the worker’s decline in performance, the risk of losing a lawsuit is much higher. Absent an objective measurement, it is your word against your worker’s word. Using a formal plan can also lead the worker to quitting voluntarily, which virtually ensures that there will be no lawsuit. Of course, you need to have an honest, candid discussion with the worker as you set the plan terms.

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FLATWORK/SLABS

By Bryan M. Birdwell and Joe Nasvik

Carbonation

in Freshly Placed Slabs The reaction between cement paste and carbon dioxide in the air.

aul Beagley started Phaze Concrete Incorporated, Hildale, Utah, in 2003 primarily to do large warehouse and “big box” floor work. Business went well and they branched out to include parking structures, specialty projects for the government, earth and utility work, and concrete polishing. They now have over 300 employees and are members of the American Concrete Institute (ACI) and the American Society of Concrete Contractors (ASCC). Over time he says his company encountered a couple verified cases of floor surfaces damaged by carbonation, but there have been other projects where excessive carbonation was suspected. “The common thread in all these projects is that the work

was completed during the winter months and unvented heaters were present,” he says. “In all cases the repairs were expensive.”

WHAT IS CARBONATION? The simplest answer is that carbonation results from the reaction between atmospheric carbon dioxide (CO2) with hydrating cement but not with carbon monoxide (CO). Normally the result of the reaction is a thin white film of calcium carbonate on concrete surfaces, also referred to as efflorescence. For instance, if you install a concrete driveway you first see the natural color of the concrete but after a day or so the surface begins to have a white cast. This is efflorescence, a harmless calcium carbonate coating that has little effect other than to change the surface color of the concrete—not to say this isn’t important, owners expect slabs to look aesthetically clean and free of white blemishes and sometimes raise payment issues. This can be serious when specifications call for colored concrete.

Unvented heating can cause serious problems to fresh concrete. This nicely finished floor carbonated within the first couple days, causing the surface to pull up when tape was removed. Photo Credit: Paul Beagley

Deep carbonation, on the other hand, can also cause concrete surfaces to be deeply weakened and this is what causes problems. By the time fresh concrete is placed and finishing operations are started, the portland cement in the concrete is beginning to hydrate, producing calcium hydroxide (Ca(OH)2) as a byproduct. It dissolves in the mix water and is the principal chemical that gives concrete its high pH. When it comes into contact with atmospheric CO2 the resulting reaction yields calcium carbonate (CaCO3), the process referred to as carbonation. When there is a lot of CO2 present the production of calcium carbonate can become extreme, damaging the surface of a floor and requiring that drastic measures to be taken. The chemical reaction is as follows: Ca(OH)2 + CO2 ------> CaCO3 + H2O Sodium hydroxide and potassium hydroxide are also present to a lesser degree in new concrete and produce sodium and potassium carbonation.

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FLATWORK/SLABS THE WAREHOUSE ENVIRONMENT General contractors are usually the ones responsible for providing background conditions, including temporary heat for enclosed warehouse construction. When floors are being constructed during the winter months the usual ambient and base temperature requirement is a minimum of 55ºF. If a buildings

permanent heating system is functioning it is used to provide the needed heat. But if it isn’t functioning, temporary vented or unvented heating systems are brought in. Vented systems expel exhaust gases (CO2 and CO) outside while unvented systems send exhaust gases along with the heat into the air inside the building. General contractors sometimes elect to rent unvented systems

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because heating with them is less expensive. During the floor construction process openings for ready-mix trucks are constantly open and ready-mix trucks are passing in and out every few minutes. Their diesel exhaust gases put a combination of CO2, CO, soot into the air. In addition, exhaust gases from laser screeds, light towers, and finishing machines also go into the air. The current Occupational Safety and Health Administration (OSHA) requirement limits the permissible exposure limit (PEL) of CO in the air to 50 ppm (parts per million) or 0.05 percent over an eight hour time period. Because of the rule, many contractors use CO detectors, or are required to use them, to monitor the air for the safety of their workers but they don’t monitor CO2 levels unless the owner requires, the typical regulation being a maximum of 4,500 ppm. There usually isn’t much airflow in warehouses either and CO2 is heavier than air so concentrations are highest at floor levels.

Unvented heaters, like the ones shown here, emit large quantities of carbon dioxide exhaust and because it is heaver than air it is even more intense on freshly placed concrete surfaces. Photo Credit: Bryan Birdwell

WHY FLOORS CARBONATE

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As mentioned earlier, there is always a minor amount of carbonation occurring to the surface of concrete (as well as a little bit in the concrete). This is because some calcium hydroxide dissolved in water moves through the pore structure of the concrete to the surface and there is always CO2 in the air available to

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Concrete loses much of it’s strength when it carbonates. A thin layer of the floor surface in this photo carbonated and peeled up with tape. Because the thickness of the damage was so small the contractor was able diamond polish the floor to get rid of it. Photo Credit: Paul Beagley

react with it. The current level in the air is approximately 400 parts per million (ppm) or 0.04% (this is about 40% more than at the start of the industrial revolution). Water is important to the process because both CO2 and calcium hydroxide are soluble in it and are carried by it, making freshly placed concrete the most vulnerable—rainfall on freshly finished concrete produces a lot of carbonation or efflorescence too because more water is available. The flooring industry uses concrete mixes that are all portland cement—no supplementary cementitious materials—with water cement ratios of 0.5 or a little above. Finishers start the finishing process after the water on the surface of the struck-off concrete subsides, an environment that encourages the formation of carbonates. Jose Pacheco, PhD, a concrete materials specialist at CTLGroup, Skokie, Illinois, says that carbonation tests performed in the laboratory are typically performed in controlled environments using 3- to 4% carbon dioxide levels in the air, translating to 30,000 to 40,000 ppm. “Depending on the cement being used, transport properties of the mixture, moisture conditions, and time of exposure, this can produce carbonation in mortar samples as deep as one inch,” he says. There is little information from the field about CO2 amounts at the surface of a floor when unvented heaters are being used but they may be approximately one percent, enough to do significant damage to a floor surface.

Factors that influence the amount of carbonation in floor surfaces include the following: • The amount of CO2 produced by unvented construction heaters and diesel engines • The type of cement being used • The water/cement ratio of the concrete—as related to the transport properties of the concrete • The amount of airflow in the building • The surface finish—how porous it is • The amount and density of cement paste on the surface

depths being as much as 1/4 of an inch in thickness. In one case Beagley says the carbonation caused the surface to be porous but the depth was minimal and they were able to diamond polish the floor to the owners satisfaction. This was agreeable to the owner in this case, but sometimes owners object. Issues such as who is at fault, who pays for the remedy and large aggregate exposure have to be resolved. Concrete contractors are almost always blamed for the problems and there can be a lot of expense involved.

HOW TO REDUCE THE RISK The most important way to reduce your level of risk as a concrete contractor is to ensure that unvented construction heaters aren’t allowed on the jobsite. Most flooring contractors include this as an item in their pre-job/slab conferences today. Beagley says he hasn’t had a problem since he decided to specify the type of heater they want on the jobsite. Concrete contrators must explain the possibility of these issues and have a cost to remedy or exclude the cost to remedy from their contracts. It’s not known at present how much CO2 is added to the warehouse environment by ready-mix trucks and other diesel engines. Many contractors have instruments that monitor CO for safety reasons but they don’t monitor CO2 levels. Using fans to move air can help reduce concentrations at floor levels. Moving exhaust out of the building is also helpful, a process that must be balanced with maintaining minimum temperatures in the building.

WHAT TO DO IF THERE IS SIGNIFICANT CARBONATION Unfortunately, contractors can find themselves having to remove and replace floors that have significant damage to the floor surface. Carbonation can turn cement paste to a powder and make a surface porous. Depths can be as little as 1/32nd to 1/8th of an inch with extreme

It is important for Vented heaters, you as a contractor such as the one shown here, can to know if the probbe placed either lem you are expeinside or outside riencing is related buildings but their exhaust to carbonation or doesn’t enter the excessive loss of enclosed space. They are more moisture on the surexpensive but face, as the two conshould always be ditions can resemble used to heat areas during concrete each other. In the placement. interest of learning Photo Credit: Bryan from mistakes you Birdwell should consider hiring a petrographer or concrete floor consultant experienced with these kinds of problems. Beagley said that he hired a petrographer for one of his jobsite failures and was told the problem was caused by carbonation. The owner hired a petrographer too and was told the problem wasn’t related to excessive carbonation. Beagley then hired a consultant to review both reports and it was determined to be a carbonation issue. But in another case he says that an assumed carbonation issue turned out to be excessive non-hydrated cement particles at the surface, attributed to no bleed water and a high rate of evaporation.

www.forconstructionpros.com/concrete | June/July 2017 | Concrete Contractor 15

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COVER STORY

By James R. Baty II

Going Out on a Limb is Easier than

BUILDING ON A CLIFF This feature connects you with the Concrete Foundation Association’s Grand Project of the Year, one of the many projects receiving recognition in the association’s 2017 Projects of the Year competition.

anadian Novelist, David Bergen once quipped, “I think a construction project for me is like writing a novel. I can’t do the project unless I can envision sort of the whole structure and see what the end result might be.” Perhaps this statement is true for the success of

every project in the built landscape today, although we are aware of more than one to which this has been called into question. Still, lost in the completion of any project is the appreciation for the vision the contractor must have to complete the seemingly impossible…most certainly the incomprehensible. Among the projects submitted for the 2017 CFA Projects of the Year sat a project weighing in at 15,000 sq.ft. (1,393.5 sq.m.). The project, a private residence in Corona Del Mar, Calif., was constructed on a cliff overlooking the coastal bay. Submitted by Ekedal Concrete, Inc. of Newport Beach, the foundation was another entry for this perennial seeker in an already impressive collection of strikingly large concrete works with massive challenges. As a company, Ekedal has made a commitment to this market in taking on any and all challenges. Their results evidence the success of combining such a vision they have for the project sequence with the skill they’ve developed as a concrete contractor to

deliver a foundation second to none and another award-winning project. One of the first questions often asked of a contractor working a project like this pertains to their selection. Ekedal Vice President Ryan Ekedal describes the merits of this project and their selection for the concrete work as having stemmed from the investment they made. Ekedal had been involved with it consecutively throughout a 10-year development timeline. “This was a very complicated project in a very affluent part of the city next to multi-million dollar homes on both sides. All of the local governing agencies were involved, along with the coastal commission, so it was a very lengthy process to get the approvals. The entire design team came to Ekedal due to our reputation and the body of work we have to show over the span of 40 years. Ultimately, our selection is based on the immense amount of time on the front end of our projects, and a project like this very much needed that. Additionally, we bring experience in expediting approval processes and

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delivering an in-house shop drawing department with complex software solutions to make the pre-construction phase very smooth.” This company put a lot at stake early in the project, developing a relationship with the design team, the owner and the builder so that every aspect of the work is controlled and delivered with confidence and precision. As seen in the images, the project sits into the side of a large cliff overlooking the ocean. This meant considerable shoring was needed to hold back the cliff. The construction sequence of drilling, pouring, shoring, re-shoring and continuing maintained the surrounding areas. Shoring walls themselves were 20 feet (6 m) tall and tapered from 8 in. (20 cm) to 20 in. (50 cm) consisting of shotcrete in separate sections due to the shoring piles needing to stay in place until the sections came to their desired strength. This private residence, in addition to the astounding square footage of the footprint, delivers quite unimaginable statistics for a residential project. Such numbers include a total of 2,910 yards of concrete (2225 cu.m.) delivered into the foundation’s structural elements including caissons, mat slab, foundation walls and podium decking. Steel reinforcement throughout came in at 1,595,000 lbs. (723.5 tonnes). Structural support for the home to be constructed within the footprint required 33 caissons,

each three feet (0.9 m) in diameter and a depth of 1500 feet (457 m). From the caissons, massive 24 x 250 steel I-beams spanned as long as 50 feet (15.2 m). Built into a cliff, the foundation walls ranged from 11 to 26 feet (3.35 to 7.92 m) in height while the thickness of the walls ranged from 12 to 18 inches (30 to 46 cm). However, what the statistics don’t tell were the complications of the design that made the construction strategies most challenging. “The complexity of this project was due to its vast size and the number of radii that the project included, some which had center points actually offsite (in the ocean)”, states Ekedal. “By working directly with the architect and engineer we were able to get needed dimensions for points and intersections at critical locations. We also made full scale mock-ups to make sure ADA compliance was

accomplished. Our in-house plan detailing department was critical in staying far ahead of the work in the field by addressing clashes.” Ekedal added much of the curved foundation walls on the project had very few tangent intersections. This made layout very complicated and critical. “Many of the points used to layout these radius walls were essentially in the middle of the Pacific Ocean. Also, each section of wall was designed with rebar cages at each end to make a "moment frame" condition.” The rebar cages, as noted by Ekedal consisted of six #5 vertical rebars with #4 rebar ties at 12 in. (30 cm) on center and two #4 hairpins at 12 in. (30 cm) on center. These added an extreme amount of labor as well as being challenging to build. The complexities of the project didn’t stop at the walls, however. A 12,570 sq.ft. (1,168 sq.m.) podium

Garage access ramp and main level structural supports for Aerie project. Photo Credit: Ekedal Concrete, Inc

Drone photo of the Aerie elevated deck pour underway in Corona Del Mar. Photo Credit: Ekedal Concrete, Inc.

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COVER STORY deck, 12 in. (30 cm) thick had a portion that sloped and a 5-1/2 in. (14 cm) thick light weight pan deck of 11,570 sq.ft. (1,075 sq.m.) was set on the floor above. Both decks feature serpentine edges and multiple steps. To achieve ADA compliance, one of the radius walls was offset at the top resulting in a sloped radius corbel detail that tied in with the sloping podium deck. However the most difficult portion, provides Ekedal, was the curved sloped 12 in. (30 cm) concrete driveway. “The driveway had an entrance lane and an exit lane which started at different locations. This resulted in differing elevations connected by a structural concrete beam or curb. Since the street the driveway exits on is sloped the drive was cambered to match but also needed an opening to allow for access into the generator room below. Then, to complete the designer’s vision, planters were constructed at the top of the driveway with curved walls, differing

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levels, and a sloping curved curb. We had very little straight wall on this immense project.” The most challenging part to appreciate of any concrete in building construction is its very existence. In a short time, the work is covered by the project it supports and the stories of how it came to be are all that remain. This is certainly true for this massive foundation supporting the multi-million dollar development adding to the Corona Del Mar landscape. And yet, there are even more stories to be told of the way the project came together as well as the material science that protects the investment. Ekedal Concrete and their product supply partners brought in waterproofing concrete admixtures, added epoxy-coated rebar and prepared the project for a lifetime of secure performance. When asked if there was one thing that stands out the most about this project and their effort to bring it through this vital stage, the president of Ekedal Concrete, Dave Ekedal, offers, “[the] Ekedal Team paying attention to all the important details is what lead to the success of this project. Working as a team and not as an individual increased the opportunity to have the success we did. From top to bottom the effort was 110%.” Ed. Note: More photos of this project can be seen in the awards section of the CFA’s website, www.cfawalls. org. To get the best perspective on the complicated work, Ekedal Concrete offers a series of YouTube videos on the project. • Walls on podium deck forming: https://www.youtube.com/ watch?v=JrBSuIjxD3M • Podium deck pour: https:// www.youtube.com/ watch?v=Up4gxkQ-taw • Wall pour: https://www.youtube. com/watch?v=BPDyfLnxzak • Mat Slab pour: https://www.youtube.com/watch?v=_hcmffBfkYY

ALL 2017 CFA PROJECT AWARD WINNERS The 2017 slate of Project Award winners that will be announced officially during the Concrete Foundations Convention in Nashville, Tenn. July 20-22 include: Single Family Residence Under 2,000 sq.ft. Blue Willow Ridge Nest #3 – SCW Footings & Foundations, Salt Lake City, Utah Single Family Residence 2,000 to 5,000 sq.ft. Bashan Lake Residence – Talpey Construction, Westbrook, Connecticut Single Family Residence Over 5,000 sq.ft. (Also Grand Project of the Year) Aerie Foundation – Ekedal Concrete, Inc., Newport Beach, California Commercial Project All Points Anson Building 8A – Custom Concrete, Westfield, Indiana Non-Wall Structural Element Burnett Residence Site Walls – SCW Footings & Foundations, Salt Lake City, Utah HONORABLE MENTION Thin Brick Concrete Overpass – Scott System, Denver, Colorado Elevated Structural Slab – Herbert Construction, Marietta, Georgia Pulaski County Egg Farm – Custom Concrete, Westfield, Indiana Axboe Residence – SCW Footings & Foundations, Salt Lake City, Utah Valley Rd, Private Residence – Herbert Construction, Marietta, Georgia Hoss Builder, Inc. – Custom Concrete, Westfield, Indiana Lake House – ABI Corp, Lee’s Summit, Missouri Blue Willow Bingham Residence – SCW Footings & Foundations, Salt Lake City, Utah Nolan Plan – Foundation Builders, Greeley, Colorado Woodworks, Inc. – Custom Concrete, Westfield, Indiana Masterpiece Bldg & Restoration – Custom Concrete, Westfield, Indiana

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18 Concrete Contractor | June/July 2017 | www.forconstructionpros.com/concrete

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SPECIAL REPORT: OSHA SILICA RULE

Are you ready? Enforcing Crystalline Silica Standard in Construction Industry begins Sept. 23.

he U.S. Department of Labor’s Occupational Safety and Health Administration delayed enforcement of the crystalline silica standard that applies to the construction industry several months to conduct additional outreach and provide educational materials and guidance for employers. Enforcement will begin in September. The Occupational Safety and Health Administration issued a final rule on silica dust exposure in early 2016, with the goal to curb lung cancer, silicosis, chronic obstructive pulmonary disease and kidney disease in America's workers by limiting their exposure to respirable crystalline silica. The rule is comprised of two standards, one for Construction and one for General Industry and Maritime. Key provisions include: • Reduces the permissible exposure limit (PEL) for respirable crystalline silica to 50 micrograms per cubic meter of air, averaged over an 8-hour shift (previous limit was 250 micrograms). • Requires employers to use engineering controls (such as water or ventilation) to limit worker exposure to the PEL, provide respirators when engineering controls cannot adequately limit exposure, limit worker access to high exposure areas, develop a written exposure control plan, and train

workers on silica risks and how to limit exposures. • Provides medical exams to monitor highly exposed workers and gives them information about their lung health. • Provides flexibility to help employers — especially small businesses — protect workers from silica exposure. • OSHA estimates that the rule will save over 600 lives and prevent more than 900 new cases of silicosis each year, once its effects are fully realized. The Final Rule is projected to provide net benefits of about $7.7 billion, annually. About 2.3 million workers are exposed to respirable crystalline silica in their workplaces, including 2 million construction workers who drill, cut, crush, or grind silica-containing materials such as concrete and stone, and 300,000 workers in general industry operations such as brick manufacturing, foundries and hydraulic fracturing, also known as fracking. Employers must limit worker exposure to respirable crystalline silica

1.85M

construction workers are currently exposed to respirable crystalline silica

MORE THAN

640,000

* Graphics provided by Robert Bosch Tool Corp.

are exposed to silica levels that exceed the Occupational Safety & Health Administration’s (OSHA) proposed Permissible Exposure Limit (PEL)

and to take other steps to protect workers. The standard provides flexible alternatives allowing employers to either use a control method, or measure workers’ exposure level and independently decide which dust controls work best to limit exposures to the PEL in their workplaces. Most employers can limit harmful dust exposure by using equipment that is widely available — using water to keep dust from getting into the air

IN 2016, OSHA REDUCED THE PEL OF RESPIRABLE CRYSTALLINE SILICA AVERAGED OVER AN 8-HOUR SHIFT BY 5X.

PRE-2016

2016

250 micrograms/ cubic meter of air

50 micrograms/ cubic meter of air

20 Concrete Contractor | June/July 2017 | www.forconstructionpros.com/concrete

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? or a ventilation system to remove it from the air. The rule provides greater compliance assistance to construction employers — many of which run small businesses — by including a table of specified controls they can follow to be in compliance. Table 1 matches common construction tasks with dust control methods, so employers know exactly what they need to do to limit worker exposures to silica. In some operations, respirators may also be needed. One example listed in the table illustrates required practices for using handheld power saws. If workers are sawing silica-containing materials, they can use a saw with a built-in system that applies water to the saw blade. The water limits the

amount of respirable crystalline silica that gets into the air. Employers who follow Table 1 correctly are not required to measure workers’ exposure to silica and are not subject to PEL. Employers who do not use control methods in Table 1 must: • Measure the amount of silica that workers are exposed to over an eight-hour day. • Protect workers from respirable crystalline silica exposures. • Use dust controls to protect workers from silica exposures above the PEL. • Provide respirators to workers when dust controls cannot limit exposures to the PEL. Continued on page 24

OSHA GUIDE DESCRIBES STEPS EMPLOYERS MUST TAKE TO PROTECT EMPLOYEES FROM SILICA EXPOSURE OSHA has released a Small Entity Compliance Guide for Construction that is intended to help small business employers comply with the agency’s Final Rule to Protect Workers from Exposure to Respirable Crystalline Silica. The guide describes the steps that employers are required to take to protect employees from the hazards associated with silica exposure. All covered must: • Provide respiratory protection when required • Restrict silica exposure from housekeeping practices where feasible • Implement a written exposure control plan • Offer medical exams to workers who will need to wear a respirator for 30 or more days a year • Communicate hazards and train employees • Keep records of medical examinations Learn more at OSHA’s silica website, www.osha.gov/silica.

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www.forconstructionpros.com/concrete | June/July 2017 | Concrete Contractor 21

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SPECIAL REPORT: OSHA SILICA RULE rig-mounted core saws/drills, these tools must be equipped with an integrated water delivery system that continuously feeds water to the blade or bit. Many models of saws Manufacturers support the new excellent for tailgate training session and drills include this feature from the silica dust ruling and continue workon location. factory and aftermarket kits can be ing with contractors to make sure Contractors can also reach out to the purchased for older models. However, they’re in full compliance. manufacturer or their dealers who offer other operations have different training and can usually accommodate David Pizzolato, group marketing manrequirements. individual contractors with on-site ager for Robert Bosch Tool CorporaThings like cutting fiber cement demonstrations and safety tips. tion, states, “Bosch is supportive board, tuck-pointing, dowel of OSHA’s effort to enhance the drilling and using handheld and Table 1: Specified Exposure Control safety of workers in the construcstand-mounted drills require a Methods When Working with tion industry. Clearly the danger dust shroud and a connection to Materials Containing Crystalline Silica from silica dust exposure still exists a dust collector. and this later enforcement date Equipment/ Engineering and Required Respiratory Along with the requirement Task Work Practice Protection and offers more time for employers for using a dust collector, Table Control Methods Minimum Assigned to meet these requirements and 1 also places requirements on Protection Factor (APF) keep workers safe. Some parts the dust collector itself – Dust of the country, including Califor< 4 hrs/ >4 hrs/ collector must provide the air shift shift nia, continue to work toward the flow recommended by the tool original enforcement date of June manufacturer, or greater, and (ii) Use saw equipped 23, 2017.” Handheld with integrated have a filter with 99 percent or power saws water delivery According to Mark Michaels, greater efficiency. (any blade system that director of product manageThe second part of the diameter) continuously feeds ment for Husqvarna Construcrequirement states that the water to the blade. tion Products, workers cutting dust collector be equipped with Operate and concrete or brick are the ones maintain tool in a filter-cleaning mechanism. accordance with most affected by the OSHA ruling OSHA adopted the National manufacturer’s and handheld power cutters or Institute for Occupational Safety instructions to masonry saws are used for this and Health’s position on a filterminimize dust type of work. On handheld power cleaning mechanism—a reverse emissions. cutters, a lot of manufacturers use • When used pulse feature on a dust collector outdoors. water to reduce dust. The trick is should preclude the need to APF10 • When used None to use just enough water to bind remove filters for cleaning. indoors or in an the dust. If workers are cutting All contractors have to APF 10 enclosed area. APF 10 pavers or bricks, you also do not be aware of the increased want a lot of water saturating the importance of dust suppression in piece to the point that the mortar won’t What can contractors do now? the work place. It has benefits that go adhere properly. The first is to take a step back and beyond health and safety, according to Vacuums are also used to reduce start observing how you or your operaLyndon Kelsey, North American sales crystalline silica from the environment. tors are working. manager for Pullman Ermator. Vacuums are one of the best solutions • What can you do with your current Safety is a driving factor in this when workers need to operate without equipment to reduce dust? increased need for dust control on jobwater – such as grinding concrete in • What additional new equipment may sites. By having equipment with dust surface preparation applications. Vacube needed to comply? This could be collectors and proper shrouds hoods ums are equipped with multiple filters a portable water tank, vacuum, etc. and boots, attached this collection is to take care of small particulate matter. • Are you using any type of protective possible. The other main reason for Another way manufacturers can help equipment – safety glasses, hearing dust suppression and collection is workers is through training. Operator’s protection, respirators? to protect other building occupants manuals that accompany equipment • How long are your operators working? during the remodel or addition. Having are useful tools for safety and training. According to Ben Kruse, marketing vacuums connected to equipment colDocumentation includes information on director for Pulse-Bac, OSHA’s lecting dust when working is key! Not dust levels and how specific levels have Crystalline Silica Rule Table 1 shows only is the vacuums airflow (CFM) and been identified. dust control methods for many water lift important, but the type of In addition to the operator’s manual, common operations. For stationary filter is crucial to collecting the smallest online user guides for handheld power masonry saws, hand saws, walkmost harmful partials from the air. cutters and other equipment are behind and drivable saws as well as

Manufacturers weigh in

24 Concrete Contractor | June/July 2017 | www.forconstructionpros.com/concrete

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DECORATIVE CONCRETE

by Greg Udelhofen

Durable Epoxy Coatings Provide Endless Design

POSSIBILITIES

Concrete Designs Enterprises takes artistic approach with epoxy floor systems to build a successful decorative business in Louisville, Ky.

ourteen years ago Jesse Barber launched his decorative concrete business by focusing primarily on overlays, countertops, micro-toppings and color staining. Within four years he began working with epoxy floor systems in order to deliver a more durable decorative finish for both residential and commercial customers. â&#x20AC;&#x153;The staining/coloring and sealing decorative application I used seemed to hold up well in non-traffic

The Zombie Dogs restaurant project consists of hand-troweled Epoxy 400 -- 50% mercury, 25% gunmetal, 25% pearl colors, with a clear Poly 325 topcoat. Photo Credit: Concrete Designs Enterprises

areas of a floor. But in commercial applications, the finish would eventually wear off, and I knew there had to be a better way to achieve the look and durability I wanted to deliver my customers,â&#x20AC;? Barber notes. He did some research and had discussions with Arizona Polymer

26 Concrete Contractor | June/July 2017 | www.forconstructionpros.com/concrete

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We are Here to Help

DUST EXTRACTION SYSTEMS FOR ALL INDUSTRIES

Pullman Ermator and its team of experts from numerous industries are here to help. With its iComply program we can help the contractor through our distribution chain with OSHA compliance. “The tools that we need to protect workers are already out there. They’re available. They’re not prohibitively expensive, and they need to be implemented.” -Deven Johnson

Director of Training, Health and Safety for the Operative Plasterers’ and Cement Masons’ International Association

What is Silica? • Silica is quartz, and is found naturally in almost all rock, sand, soil, brick and concrete products • Respirable crystalline silica particles penetrate deep into the lungs causing lung disease • Silica exposure remains a serious threat to nearly 2 million U.S. working, including more than 100,000 workers in high risk jobs such as abrasive blasting, foundry work, stone-cutting, rock drilling, quarry work and tunneling

How do I Comply? • Exposure determination • Use Table 1 or Monitor exposure • Create a written exposure plan • Designate a competent person

• Provide medical surveillance • Provide proper training • Required recordkeeping • Use proper HEPA dust collection

Go to www.iComplysilica.com

To see a list of presentations to find one near you

How to Choose a HEPA Vacuum Important points of requirements • High quality HEPA filters that are tested and certified, with a rating of at least 99.99 at 0.3 micron • 25 CFM PER BLADE INCHES REQUIRED FOR HAND GRINDERS • High CFM & Water Lift for proper matching to equipment • Must have a mechanical filter cleaning method, contained allowing no dust to escape • Multi levels of filtration, that include a cyclonic chamber, prefilters, HEPA’s and pre-separators • Drop down bagging containment systems, no dust can or tray • Availability to attach tools for collection at the source • Wet and dry availability when needed

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DECORATIVE CONCRETE The Mellow Mushroom restaurant dining area consists of hand-troweled Epoxy 400 mercury, coffee, pearl and blue mixture, and gunmetal and blue mixture, with a clear Poly 325 topcoat. Photo Credit: Concrete Designs Enterprises

Flooring, a supplier of epoxy floor systems, and began working with epoxy and polymer products to design and deliver the quality projects that have propelled his growth for the past 10 years. Today, 75 percent of Barber’s work is residential and the remaining commercial. He’s supported by one employee in the field and his wife, Debbie, who handles all office responsibilities.

POLY PERFORMANCE “When we started working with epoxy systems that included a clear polyurethane finish, we noticed how much more durable it was over the sealer coat we used on previously stained floors,” Barber explains.

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That was clearly a defining moment for Barber in his quest to deliver a high-quality floor for his customers. “You can design and create a great looking floor, but if it doesn’t hold up, it’s going to start showing wear and tear, and customers are not going to be happy,” he states. “The more durable the finish the longer the floor will maintain the high-end look you and your customers want. Polymers are more scratch resistant, superficial in most cases, with most abrasions easy to sand out before applying a new finish coat. Two recent commercial projects, both trendy restaurants, illustrate the design depth and quality Barber has been able to achieve with epoxy floor systems. The 2,400 sq.-ft. Zombie Dogs’ project in Dayton, OH displays a metallic industrial look Barber achieved by hand-troweling three colored epoxies (400) – 50 percent mercury, 25 percent gunmetal and 25 percent pearl. With half the floor surface new concrete and the other older, Barber lightly grinded the entire surface to open it up for the base gunmetal epoxy coat, which served as a primer coat. The following day he lightly sanded the base coat before hand-troweling the mercury and pearl epoxies to create the variegated look.

“You pour out beads of the different epoxies and then trowel them together to form the color and pattern variation you want,” Barber says. “The thicker viscosity of the epoxies used creates the depth of the finished design. The color, metallic chrome and thickness of the epoxy all work together to give the finished project the depth you see. When you pour heavy and hand trowel or use a magic trowel (rubberized squeegee), you can control the depth of the design.” On the third day, Barber lightly sanded the surface before applying a final clear topcoat polyurethane 325 finish. In the kitchen area of the project, the same color design was used, but a topcoat polyurethane Epoxy 600 with 60 grit aluminum oxide was

Residential project features a Color Chrome Epoxy 400 mercury base with a CC epoxy three-color specialty blend, with a Poly 501 topcoat. Photo Credit: Concrete Designs Enterprises

28 Concrete Contractor | June/July 2017 | www.forconstructionpros.com/concrete

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SHOW DUST AND SLURRY WHO’S BOSS WITH THE DEX SYSTEM DEX is a dust management system developed by Husqvarna Construction Products to control water and dust created while cutting concrete, asphalt and other materials. The system makes it easy to set the exact water flow for any application, which minimizes water consumption and slurry. DEX also enables contractor to use portable water tanks for much longer, increasing cutting time and therefore production. The DEX system can help operators comply with new OSHA Silica regulations.

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CONC0617_26-31_Decorative.indd 29

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DECORATIVE CONCRETE A residential project was created using a walnut acetone dye with added black stain achieve texture and marble look. Photo Credit: Concrete Designs Enterprises

used to provide a safer and a more sanitary surface to maintain in the food preparation area. On the Mellow Mushroom restaurant project in Louisville, Barber designed a multi-area color chrome abstract and blend layout using four Epoxy 400 colors – mercury, coffee, pearl and blue mixture, and gunmetal and blue mixture. Once again, Barber began the project with a light grind of the new 3,000 sq.-ft. concrete floor to open the surface to allow for strong adhesion of the epoxy coatings. Before applying the first color, he used a Mongoose decorative concrete saw to score the pattern used to create the design. Taping off adjacent sections, Barber began by applying the outer sections first. The following day he taped off the outer sections before applying the pearl and blue middle section. “When you have a pattern to create it’s more about the logistics of what can you get to when deciding where to start,” Barber says. “You also have to make sure you can complete a section before it begins to set up. That’s why I often create a defined

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30 Concrete Contractor | June/July 2017 | www.forconstructionpros.com/concrete

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The growth of Barber’s epoxy floor business over the past 10 years seems to reflect the trend he sees in the Louisville area, as well as that of the industry in general. “For me and my customers it’s a matter of maintenance and clean-ability. Epoxies with polyurethane topcoats are just more durable and resistant to spills and staining,” he explains. “In food environments in particular, a spill can be quickly and easily addressed with a dry mop and then cleaned on a regular basis with a wet mop. That’s all it takes to maintain a good-looking surface.”

Daniel Owen, owner and president of Arizona Polymer Flooring, agrees with Barber regarding the growing trend in epoxy floor systems. Owen talks about “the uptick in metallic epoxies over the past five years” as the driving force behind the increased interest for the high-end look that can be achieved. But he’s quick to point out that achieving and maintaining a high-end look requires a clear polyurethane topcoat. “Without it, the floor will become dull within a short time,” Owen says. “The aesthetics, and easy to clean and maintain qualities of an epoxy floor system with a clear coat of urethane will look good and last longer. And the metallic epoxy systems have really helped (decorative concrete) contractors help their customers achieve the unique modern look they want.”

S I GNE

AN EPOXY TREND

That’s not to say other concrete finishing options, like polishing, do not deliver the look and performance customers want, it’s just been Barber’s experience that epoxies deliver a more stain-resistant surface in environments like restaurants. What Barber has done to set himself apart from other decorative concrete contractors is to offer a more artistic custom look to the floors he installs. “I custom blend the colors and looks that appeal to the clientele I serve, and while it may be a little more expensive, it helps to market the kind of results I’m capable of achieving,” Barber says. “We’ve done some jobs using just a gunmetal epoxy and they’ve turned out great, but the Zombie Dogs’ project (with added mercury and pearl epoxies) is what you’ll remember. And I think that’s the unique trend in floor designs customers want.”

seam at thresholds between rooms as a way to execute a large project over the course of several days.” After completing all color applications, Barber grouted the score lines separating the colored sections and then applied a Poly 325 topcoat.

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www.forconstructionpros.com/concrete | June/July 2017 | Concrete Contractor 31

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SPECIFICATION GUIDE: CONCRETE SAWS

Concrete Saws

A compilation of technical information when choosing your next concrete saw.

1 U.S. Saws’ Early Entry Saw

U.S. Saws’ Early Entry Saw is an electric powered, portable and lightweight saw for cutting green concrete. • •

Spring-loaded skid plate allows the saw to cut new control joints in green concrete without making an impression in the concrete. Wide wheels and thick axles make the saw durable and allow it to track straight

ForConstructionPros.com/12025473 Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

Early Entry Saw

36” x 10” x 42”

48 lbs.

7/8”

7” - 8”

250”

2”

Electric

2 CS8 Random Crack Saw from General Equipment

The CS8 Random Crack saw uses 8-in.-diameter dry cut-type diamond blades to produce smooth-sided cuts for proper crack filling. • 1/2-in. maximum cutting width and 1-1/2-in. maximum straightline cutting depth • 11-hp Honda engine with Cyclone-type air filter system • Center-mounted blade configuration minimizes undercutting • Infinitely adjustable blade height control ForConstructionPros.com/10078454

Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

CS8 Random Crack Saw

52” x 27.5” x 43”

290 lbs.

1”

8”

Dry, 8”

1.5”

13 HP Honda 4-stroke gas engine

3 Husqvarna K 760

The Husqvarna K 760 is the perfect all-around power cutter. It features the lowest vibration level, 2.4 m/s2, on the market along with a fuel-sipping X-Torq engine, which optimizes performance. It also comes with DEX, dust suppression system, that helps minimize dust and water usage. It can be used for a variety of cutting applications including curbstones and pavers in landscaping, metal/pipes in installation work, concrete in buildings as well as roadwork applications. 1 year manufacturer warranty. ForConstructionPros.com/10093940 Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

K 970 14”

26.02” x 8.43” x 17.48”

24.3 lbs.

1”and 20 mm

N/A

14”

5”

Gas

Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

K 6500 16”

26.8” x 7.4” x 19”

22 lbs.

1”

N/A

16”

6”

High Frequency Electric

Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

K 760 14”

23.66” x 8.86” x 15.31”

21.6 lbs.

1” and 20 mm

12” - 14”

14”

5”

Gas

32 Concrete Contractor | June/July 2017 | www.forconstructionpros.com/concrete

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4 Hilti DCH 300

The Hilti Electric Diamond Cutter DCH 300 sets standards in performance, safety and comfort for applications where cutting dry is a must. With a 2.6 kilowatt motor and cutting depth adjustment, the DCH 300 reaches a depth of 4-3/4 inches. Consider pairing the DCH 300 with the new Hilti VC 300-17X vacuum which includes a 17-gallon tank, filter cleaning mechanism and 99% filter efficiency for a dust controlled, dry cutting option. ForConstructionPros.com/20863165 Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

DCH 300 Electric Concrete Cutter

27.8” x 9.4” x 9.3”

20.7 lbs.

7/8 in; 22.2 mm

12”

4 ¾”

Electric

5 SRX-150 Green Cut Early Entry Saw

MK Diamond’s SRX-150 Green Cut Early Entry Saw is engineered for sawing crack control joints. It comes with a Honda GX 160 Cyclone Air Filtration engine or Kohler CH255 engine. The SRX-150 has an upcut blade rotation, which facilitates in keeping debris out of the joint. The anti-spall, skid plate aids in keeping the edge of the joint smooth. The blade guard features a 2-in. vacuum port for easy connection to dust control systems. ForConstructionPros.com/12258752 Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

SRX-150

32” x 19” x 42”

88 lbs.

Triangular

6-3/8”

N/A

1-1/8”

Gas

6 Chicago Pneumatic SCG 350

Chicago Pneumatic concrete and asphalt floor saws are designed to deliver a straight, stable cut. They’re also operator-friendly, thanks to adjustable handles and perfectly positioned controls. Both gasoline and diesel models are available, and all come with the reliability and simple maintenance. The CP floor saws offer a maximum cutting depth of 5.9 inches to fit most job requirements. Suitable for cutting expansion joints, they can also be used to cut asphalt for road maintenance and as an alternative to jack hammers. ForConstructionPros.com/20863094 Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

Chicago Pneumatic SCG 350

N/A

215 lbs.

N/A

13.8”

N/A

3.9” to 5.9” max

Gas

7 CS Unitec Saws for Wet or Dry Cutting

From small to large jobs, CS Unitec offers an array of portable concrete cutting saws. • • •

7” EDS 181 for smooth cuts up to 2-1/2” deep and includes integrated vacuum port. 18” CSH 150 handheld pneumatic saw for cuts up to 7” deep with 9.5 hp low-maintenance motor and built-in water connection. 20” CSR 150 walk-behind pneumatic saw for cuts up to 7” deep 9.5 hp motor with gearbox drive.

ForConstructionPros.com/20863137

Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

CSR 150

52” x 14” x 35”

107 lbs.

1”

12”-20”

20”

7”

Pneumatic

Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

CSH 150

26” x 12” x 18”

28 lbs.

1”

14”-18”

18”

7”

Pneumatic

www.forconstructionpros.com/concrete | June/July 2017 | Concrete Contractor

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SPECIFICATION GUIDE: CONCRETE SAWS

Diamond Products Announces Gas Powered Large Walk Behind Saw Diamond Products Limited announces its new addition to the existing large walk behind line with the CC6561GK Kubota 61 horsepower gasoline saw. This saw has the reliability, power and convenience you deserve while cutting in large, high production applications. With a digital control panel, electronic engine controls, 17-3/4” cutting depth and the strongest frame on the market, the CC6561GK is well equipped. ForConstructionPros.com/20863146

Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

CC6561GK

62” x 31-1/4” x 55-1/2”

1,800 lbs.

1”

14”-42”

42”

17-3/4”

Gas

Skilsaw 7 in. Medusaw Worm Drive Saw for Concrete, SPT79-00 Skilsaw says Medusaw is the world’s first fully integrated saw designed specifically for scoring and cutting concrete accurately. Its Skilsaw worm drive power train, plus a unique Cut-Ready adjustable plunge lock and a pivoting pointer aim to improve precision and convenience. Used wet or dry, the dual integrated dust management system takes dust out of your way. Rust-resistant brackets and fasteners resist corrosion for long life. ForConstructionPros.com/12293671 Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

SPT79-00

7.5” x 19.5” x 7.75”

16.9 lbs.

7/8”

N/A

2” at 90°

Electric

10 PB50 Early Entry Saw from Packer Bros.

The PB50 Early Entry Saw shares features found on other green cut saws, combined with the best innovations and manufacturing quality found in the Packer Brothers existing Extreme line of concrete saws, mini-groovers, and random crack chasers. Built at Packer Brothers’ Minnesota facility for quick factory direct shipping, you’ll appreciate the rugged frame, dust side chute, rubber boots that prevent skid pin sticking, and the universal arbor design that accepts all the popular blade brands. See why professionals that demand quality and value look to Packer Brothers. ForConstructionPros.com/20863152 Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

PB57 EXTREME

17 x 45 x 36”

98 lbs.

5/8”

6” - 7”

7”

2”

Gas

11 iQ360x 14-in. Masonry Power Saw from iQ Tools

Equipped with a 1.75hp motor, the iQ360x 4-in. Masonry Power Saw with Fully-Integrated Dust collection has been tested to capture 99.5% of the dust giving a contractor the ability to cut indoors and out. • • • •

This OSHA-Compliant unit cuts stone, brick, pavers and tile up to 4.5-in. high and 12-in. long and is compact and light-weight for easy transport The unit’s 92 CFM high output vacuum sucks the dust through the retractable blade guard Using the iQ QUICK-SPIN filtration system, the dust is captured in the cartridge filter and then selfcontained in the lower chamber for easy disposal, easy cleanup and recycling This dust containment has a capacity of up to 50 lbs.

ForConstructionPros.com/12296149 Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

iQ360x

20” x 17” x 31”

65 lbs.

1”

14”

N/A

4.5”

Electric

Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

iQPC912v

13” x 42” x 16”

31 lbs.

1”

12”

N/A

4”

Gas

34 Concrete Contractor | June/July 2017 | www.forconstructionpros.com/concrete

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12 Allen Engineering APS20H Compact Saw

The Allen APS20H is a compact saw with powerful attributes. It features a high-horsepower engine with deep-cutting abilities, and is highly maneuverable. ForConstructionPros.com/12213528 Model

Product Size (LxWxH)

Weight:

Arbor Size

Blade Diameter Range, min-max

Diamond Blade, max

Max Cutting Depth

Power (electric or gas)

APS20H

62 “ x 22” x 43”

348 lbs.

N/A

12” – 20”

N/A

7”

Honda GX390 (389 cc) Engine

POWER TROWEL SPECIFICATION GUIDE

The March 2017 issue of Concrete Contractor featured Power Trowels. Regretfully, we omitted a submission.

13 MBW Introduces F36 and F46 Walk-Behind Trowels

New in 2017 from MBW Inc. are two new walk-behind trowels, the F36 and F46. Highlighted features include: • • • •

Patent-pending Low Vibration handle is multi axis shockmounted 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

ForConstructionPros.com/20858037 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 rpm

N/A

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 35-180 rpm

N/A

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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www.forconstructionpros.com/concrete | June/July 2017 | Concrete Contractor

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CONCRETE SCIENCE

By Joe Nasvik and John Gajda

thermal cracking Why it happens and how to control it.

t’s often said that what we know about concrete is that it gets hard and it cracks. But this is a meaningless oversimplification because it doesn’t tell us anything about either the hardness in concrete or cracking. Sometimes concrete doesn’t get hard enough and at other times it gets too strong. Cracking isn’t a given with concrete, sometimes for unexplained reasons it doesn’t crack at all. There are many forces within a concrete element and if you don’t want concrete to crack the forces must be understood and

controlled starting with the planning stage. One of the reasons concrete cracks is due to “thermal cracking” and this relates to the temperature development as concrete hydrates as well as temperature differences within a slab. Thermal cracking is also dependent on temperatures surrounding a slab such as ground and air temperatures. Here are some of the conditions that can cause thermal cracking to occur, conditions you should be aware of and plan for.

MASS CONCRETE There is an increased focus on mass concrete now because of the demands placed on it. Concrete

Thermal cracking is usually associated with mass concrete but it can also happen to thinner slabs because of temperature differences between concrete ground, and ambient temperatures. Photo Credit: John Gajda

elements are getting larger, there are often requirements for increased flowability during placement, the construction of structures proceeds at increasingly faster speeds so owners and contractors expect mass concrete slabs to reach designed strengths faster, and owners are beginning to specify long service lives without significant maintenance—wanting better performance.

36 Concrete Contractor | June/July 2017 | www.forconstructionpros.com/concrete

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DECORATIVE AUG.17-19., 2017 Surpass your competition by attending the Decorative Concrete Fair. Innovative trainers, best-in-class contractors, and industry experts will teach you to stamp, stain, polish, and more. Set yourself apart. Earn more. Grow your business. Only $50 gets you full access to the best value in training! Drop your trowel, pick up a corndog, and join us at the Decorative Concrete Fair August 17 -19 in Springfield, IL. Early registration special: Only $50 for all 3 days! (Registration at the event: $100 for a 3-day pass) www.decorativeconcretefair.com

Learn From Some Of The Biggest Names In The Industry

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CONCRETE SCIENCE Shown here are temperature sensor wires. The thermal sensors are wired to locations all over the rebar reinforcement. Photo Credit: John Gajda

The problem with using portland cement in concrete is that it generates a significant amount of heat as it hydrates. Placed in small quantities and thin slabs, this heatof-hydration dissipates evenly and quickly but with mass concrete elements such as deep and wide foundations, piers and columns, matslabs and walls, the temperature in concrete can increase faster than it escapes. High temperatures and temperature differences between the center of the mass and the surfaces can cause thermal cracks to develop. There are differences of opinion about what constitutes mass concrete in terms of dimensions, but

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38 Concrete Contractor | June/July 2017 | www.forconstructionpros.com/concrete

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generally it is regarded as concrete elements with minimum thicknesses of four to six feet. Most people agree that any concrete element that is 4-ft. thick or greater should be regarded as mass concrete. But the characteristics of the concrete mix used also help define mass concrete. For instance, mixes which include greater amounts of portland cement develop much more heat so form sizes must be smaller. Some project specifications increase the risk of thermal failure by changing the definition of mass concrete (to increase the thickness) to avoid the added expense of designing low heat-of-hydration mixes. This poses a risk for contractors due to thermal crack development because the element really was mass concrete. Contractors need to understand what mass concrete is and isnâ&#x20AC;&#x2122;t and then cover the issues in pre-construction meetings.

The most effective way to manage thermal cracking in mass concrete applications is to use concrete mix designs which have a reduced temperature rise (i.e. a lower heat of hydration). This usually involves replacing some of the portland cement in the mix with class F fly ash, slag cement, or a combination of both. Specifications for a project usually define the highest concrete temperature allowed for a placement and the maximum temperature difference allowed between the interior and surface of the placement. Most specifications today require that temperatures not exceed 160ÂşF in any location and no more than a 35ÂşF temperature difference. When thermal cracks result in a mass concrete element, the structural integrity of the concrete can be compromised, and contractors are usually seen as the one with most financial responsibility. This is sometimes the

case, even when they did not exceed the specified temperature or temperature difference limits.

OTHER REASONS FOR THERMAL CRACKING Contrary to what you might think, thermal cracking can happen to work much less than four feet in thickness. An example would be an exterior 8-in. thick slab-on-grade. Some of the conditions that can cause thermal cracking include the following: Very high portland cement content. Mixes containing high amounts of portland cement generate more heat than mixes with lesser amounts of portland cement. Mixes that include replacement of some of the portland cement with class F fly ash or slag cement produce a reduced heat-of-hydration. Ambient conditions. Concrete temperatures which exceed air or ground temperatures by more than

ForConstructionPros.com/10303328

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CONCRETE SCIENCE

LevMix Mobile Mixer

The new LevMix unites three steps in one operation: • • •

mixing transporting pouring

The new LevMix mobile mixer combines the attributes "FAST and EASY". Mix several bags in the shortest time.

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35ºF can cause thermal cracking. Concrete temperature. The higher concrete temperatures are above ambient temperatures, the greater the risk of thermal cracking. Concrete temperatures which are over 10ºF higher than the daily high or low temperature can cause problems. As a general rule the risk of thermal cracking increases as the concrete temperature increases. Hot water added to concrete for cold temperature placement. In cold weather concreting conditions ready-mix producers often use hot water to batch concrete in order to accelerate the initial set. They arrange for concrete temperatures to be 65º to 75ºF when placement starts on the jobsite. Thermal cracking can result because air temperatures are more than 10ºF lower.

HOW TO CONTROL THERMAL CRACKING The best way to avoid thermal cracking is by designing concrete mixes that produce less heat-of-hydration, mixes designed for the requirements of a given application. Mass concrete placements usually involve working with expert consultants who can design mixes that meet the requirements of the job. In some cases mass concrete placements may involve installing cooling pipes in the concrete to moderate temperatures but increasingly temperatures

The area not insulated in the center of the photo can dissipate energy in a much wider area than the actual area of the exposure. Photo Credit: John Gajda

are being controlled with the design of the mix alone. For mass concrete mixes, the portland cement replacement is often as high as 50 percent when fly ash replaces portland cement, and 75 percent when slag cement replaces portland cement. After concrete is placed, the best way to insure the temperature difference doesn’t exceed 35ºF in the placement is to cover the work with insulating blankets as soon as possible after placement. Taking this precaution prevents temperatures at any location from decreasing too rapidly. The blankets are kept in place until the highest temperature of the casting decreases to safe levels. Care must also be taken to remove blankets when there won’t be thermal shock to the concrete caused by ambient temperatures. When ready-mix temperatures are high, as is often the case in hot

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The contractor did a careful job of insulating the concrete to prevent temperature differentials greater than 35°F. However, the vertical rebar must also be insulated because steel is a good conductor of heat. Photo Credit: John Gajda

digital infrared thermometers is a good way to do this as they quickly measure ground, ready-mix and slab surface temperatures

FINAL THOUGHTS weather, there can be some initial reduction in early hydration temperatures by replacing some of the batch water with ice or by pre-cooling the ready-mix with liquid nitrogen. Contractors and engineers are very sensitive to cost and so it’s natural to think about how to do things in the least expensive way. However the risk of thermal cracking can be high, especially in mass concrete elements, so it’s important for contractors to include all the related costs when they estimate work. As stated earlier, all types of concrete applications can be susceptible to thermal cracking, including slab-on-ground projects. To avoid thermal cracking issues it’s important to keep temperature differences between the ground, concrete, and ambient to within 35ºF degrees of each other. Contractors should keep up with weather reports and monitor ready-mix and ground temperatures to avoid problems.

Thermal cracking can affect the structural integrity of concrete and can be a very expensive problem to resolve when it occurs. For mass

concrete work, proper planning involving expert help in the design of mixes as well as careful monitoring temperatures after placements is the best way to avoid problems. For all concrete work you need to be aware of what causes thermal cracking and know what to do before any concrete is placed.

MK Diamond Products SRX-150 Green Cut Early Entry Saw Compact and lightweight, the SRX-150 dry cutting saw is engineered for early entry sawing of crack control joints within one to two hours of concrete finishing. • “Upcut” blade rotation facilitates keeping debris out of the joint • Honda GX160 Cyclone Air Filtration engine • Triangular shaped arbor • Vacuum port for easy connection to dust control systems • Anti-spall, quick change skid plate included

There are five diamond blade types to choose from based on the hardness of the aggregate in the concrete. GC-10

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MONITORING When mass concrete is being placed electronic temperature sensors are cast into the anticipated hottest and coolest locations of the placement. The more sophisticated monitoring systems on the market can log temperatures, automatically send the information to office computers via the Internet, and even sound alarms when temperature limits are exceeded so that workers can make immediate corrections. Some of these monitors also plot concrete maturity, providing contractors the opportunity to remove forms as soon as desired strengths are attained. For monitoring slabs that aren’t considered mass concrete it’s more important to make decisions based on weather reports and measuring local conditions. Using non-contact

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Highly productive crack chasing saw for cutting concrete or asphalt. Cuts 6’ to 8’ per minute depending on material being cut. 1-1/8” maximum cutting depth with 8” blade. Highly maneuverable - uses small diameter dry diamond blade allowing for tighter turning radius. • Honda GX270 or Honda GX390 engine • Pivoting wheels for easy maneuverability • Vacuum ports for convenient connection to dust collector • Depth control knob for quick adjustments MK-8000 V-Segment Diamond Blades provide a perfect fit into cracks.

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