13 minute read
Structural Practices
practical knowledge beyond the textbook There appear to be two schools of thought on cast-in-place concrete specifications. The first school likes to separate the cast-in-place concrete into three separate master specification sections; 031000 – Concrete Forming and Accessories, 032000 – Concrete Reinforcing, and 033000 – Cast-in-Place Concrete. The second school likes to keep the entire section together (as distributed by many master specification libraries) named 033000 – Cast-in-Place Concrete. Both schools have the ability to produce clear, correct, concise, and complete specifications. Both schools could benefit from some additional educational opportunities as summarized by the following two hypothetical educational courses.
Concrete Specifications 101
As the course number implies, this course covers the basics of concrete specifying: 1) What version of Concrete Specifications MasterFormat (or another guideline) is Education 2) to be used? Is the project attempting to attain By Renee Doktorczyk, AIA, CCS, CSI, SCIP 3) 4) LEED certification? What is the format for the specifications? Is the terminology consistent between the specifications and the drawings? Will the project be written to conform to the 2010 version of MasterFormat, or the 1995 version? MasterFormat, produced by the Construction Specifications Institute, is the numbering system used in the construction industry to organize specifications, cost estimating documents, product data, and even architectural libraries. An easy way Renee Doktorczyk, AIA, CCS, CSI, SCIP is an architectural specifier and the president of ArchiTech Consulting, Inc. in Mount Prospect, Illinois. She can be reached at rdoktorczyk@architechspec.com. to tell the difference between the two versions is by the length of the section number: the 2010 version uses six digits, while the 1995 version used only five. Is LEED a factor in the scope of the project? LEED, Leadership in Energy and Environmental Design, is a process of certifying a project to varying levels of environmental friendliness. The rating system was developed by the U.S. Green Building Council. The process not only affects the drawings, but also the specifications. If it is determined that the project will attempt to obtain one of the levels of LEED certification, asking for and using the LEED scorecard during the development of the specifications is important. Like drawings, specifications also need to follow a specific format. Format items to be requested and incorporated into a specification include, but are not limited to font, header and footer requirements, margins, and watermarks (if any). Consistent terminology is required for a well coordinated set of documents. The specifications will call out a vapor retarder. However, many times, a more proprietary term will show up on the drawings. For example, instead of the term vapor retarder, the term Stego WrapTM may be used. The use of proprietary terminology on the drawings does not easily allow for other manufacturers to bid on a project. Changing the term to its non-proprietary version allows the specifications to determine the manufacturers that will be allowed to bid. If help is needed for a correct non-proprietary term, contact the project’s architectural specifier.
Concrete Specifications 201
This course covers advanced cast-in-place concrete specifying, including topics on editing manufacturer lists, below grade vapor retarders, floor and slab treatments, liquid floor treatments, and concrete finishing. One of the often overlooked, but easy editing tasks is to edit the list of manufacturers for every product included in the specifications. Many structural engineers leave the entire list as it was distributed in master specification in the project specification. It is well known that if there are seventeen different manufacturers listed for a curing and sealing compound that not all manufacturers’ products will have an equal quality level. It is up to the structural engineer to select the products. If there is truly no manufacturer preference, only that the product complies with the indicated ASTM standards, then delete the entire list of manufacturers. The days of throwing a sheet of visqueen below the rebar prior to a concrete pour are over. Below grade vapor retarders have become more sophisticated. The floor finishes installed over concrete slabs on grade have become less tolerable of moisture migration through the concrete slab. As a result, the structural engineer and the architect need to coordinate not only what vapor retarder is being used, but where it is being specified. Some architectural specifiers have moved to specifying the below grade vapor retarders in the Division 7 sections with the waterproofing, damp proofing, or air barrier products in an effort to have single responsibility for the building envelope moisture control. Since many manufacturers produce vapor retarders, waterproofing, and air barriers, architects like to have one manufacturer for all of these products because of transition details and compatibility issues. As a result, structural engineers need to verify whether or not the vapor retarder will be included in the cast-in-place concrete section and what type of vapor retarder is required, especially if there is a specific product required.
Many structural engineers leave floor and slab treatments in the cast-in-place concrete specifications. Many architects don’t even know what these product entail, let alone require them on their projects. Floor and slab treatments include slip-resistive emery aggregate finish, slip-resistive aluminum granule finish, metallic dry-shake floor hardener, pigmented and unpigmented mineral dry-shake floor hardener. In this instance, it is better to take the floor and slab treatments out of the specification. There are projects requiring some of these products, but the majority of projects do not. Regardless of whether or not the floor and slab treatments are required in a project, the question needs to be asked of the architect. In addition, if none are required, be sure to delete the products out of Part 2 and the installation out of Part 3. Similar to floor and slab treatments, many times all of the liquid floor treatment products are kept in a section. These products are used more frequently than the floor and slab treatments, but not frequently enough to err on the side of leaving them in the specification. More often than not, the structural engineer should err on the side of automatically removing the products and adding them
Visit LiteSteel on Facebook back in if truly required. The penetrating liquid floor treatment product included in the master specification section is intended to be a hardener and densifier for high traffic floors (think warehouses and distribution facilities). However, when architects say they want a clear concrete floor sealer, they usually mean a second coat of curing and sealing compound, not a true concrete floor sealer. Liquid floor treatment products also include treatment for polished concrete floor surfaces. Polished concrete flooring for the most part is still in the kindergarten phase. The products included in the cast-in-place concrete floor system are not for the architecturally finished polished concrete flooring system. They are geared more toward the warehouses and distribution centers. Architectural polished concrete floor systems are covered in a separate section that will include the densifiers, the penetrating sealer, and sheen of the finish, and the amount of the aggregate to be exposed. Again, if a polished concrete flooring system is desired, verify with the architect whether it is to be specified in the cast-in-place concrete section. Concrete finishing expectations of the architect always requires coordination. Architects always want the best finish, but the budget rarely allows it. Out of all of the finishes that can be left in the cast-in-place concrete section for formed surfaces, the one most frequently kept is the smooth rubbed finish. Floor slab finish expectations also need to be coordinated with the architect, especially in regards to floor flatness and floor levelness. Verify whether the architect wants to pay the contractor to form a flat floor, or if cement based hydraulic underlayment will be specified to achieve the desired floor flatness and levelness if tighter tolerances are required for a specific project. If there is a specific finish required for a project, confirm whether a mockup is required for the finish. As budgets are being cut and architects are adapting to the change by accepting concrete as it is cast, more architects are requiring mockups for the cast-in-place concrete for review and verification of the accepted finishes during the construction period. The two cast-in-place concrete specification courses mentioned above have the ability to improve the caliber of the castin-place concrete specifications for a project. Better specifications can translate into fewer requests for information and a smoother running project.▪
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Foundation Companies Taking Advantage of Current Events and Trends Bids Now More Realistic
By Larry Kahaner
In a still weak economy, some foundation companies are exploit- FitzPatrick also notes that the recession has skewed project estiing recent trends and events to improve their bottom line. mates that are just now beginning to unwind. “Four years ago, For example, Subsurface Constructors, Inc. in St. Louis estimates were provided during the design stage before the recession (www.subsurfaceconstructors.com) is capitalizing on the had hit. When projects actually came up to bid, there was so much ‘going green’ movement by improving soil beneath wind turbine competition that it drove prices down to unrealistic levels. Now, installations. “People don’t think about the wind turbine industry in estimates have become more realistic but budgets are still being general, or about ground improvement in particular, because they squeezed, so there are a lot of owners looking for cost savings on think it’s only one pole,” says Lyle Simonton, Director of Business projects. We’re helping our clients save money but making sure Development. “People don’t realize that there’s a lot of stress on wind that estimates are realistic.” (See ad on page 33.) turbine bases. ey sit on a huge mass of concrete, a big pedestal that you don’t see because it’s all below ground, and sometimes that soil needs improvement.” A typical wind turbine pedestal sinks beneath the surface at an angle for about ten feet and can be about 65 feet wide at the bottom, says Jim Hussin, Director at Hayward Baker Inc. headquartered in Odenton, Maryland (www.haywardbaker.com) also has noticed the price dislocation of estimates and is using it to their advantage. “Although the overall U.S. construction market Simonton. “ at’s what we’re supporting on stone columns.” remains tight, we have seen a slight improvement in our margins. He notes that his company has been expanding away from their We have accomplished this with clients who, in addition to requirMidwest home turf. “We have switched from being predominantly ing a fair price, see value in our ability to recognize, communicate a St. Louis area, deep-foundation contractor into more of a and control risk. Many of these clients have experienced the false national ground improvement contractor over the last five years as economy of working with contractors who priced the work at desa result of the economy driving us in that direction. There aren’t perately low levels, stumbled while performing and then sought to as many deep foundation opportunities as we used to see locally, recover their losses through claims.... A lot of customers who went so we have had to adjust and chase the work a lot further out. We for the lowest price realize now that it wasn’t a bargain at all.” He have been successful doing so.” As for the overall market, Simonton sees the private sector coming back a bit, but Wave Equation Analysis of Piles there still is a lot of public work. “We’ve been doing a huge amount of transportation work in Indiana, Oklahoma, Run GRLWEAP to: Wisconsin and Illinois.” Select the right
Bpile driving hammer rendan FitzPatrick, Director – North America for Geopier Establish the Foundation Company in driving criterionMooresville, North Carolina (www.geopier.com), says that his company is helping SEs deal with earthquakes Now also in Offshore Wave Version in areas that had not previously experienced them. “ e earthquake that occurred in August, 2011 near Mineral Springs, Virginia, has provoked lots of discussion about seismic codes. We’re seeing a greater focus, a greater emphasis on liquefaction mitigation solutions and designs for seismic events after this rare Cleveland, OH USA +1 216-831-6131 East Coast quake.” www.pile.com/pdi/grlweap sales@pile.com
says that during the worst part of the downturn, Hayward Baker was able to charge reasonable fees, in part, because they understood risk. Some rms downplayed risk and got themselves into nancial trouble, he adds. Like others, Hussin says that public projects are still the strongest source of work but that Congress’s inaction on some funding matters is injecting uncertainty into the marketplace. “ e biggest question out there is: ‘what is the federal government going to do next?’ ere’s just so much that needs to be done in the transportation system, and also in the dams and levees sector.” Currently, the company is working on the ornton Composite reservoir in Chicago, and just completed the Wolf Creek Dam in Kentucky. (See ad on page 34.)
Pile Dynamics (www.pile.com), and its sister company GRL Engineers in Cleveland, is helping foundation companies increase pro ts with a product that can cut testing time and give a fuller reading of any aws, according to Gina Beim, senior consulting engineer – marketing. e ermal Integrity Pro ler or TIP, now in post-beta testing in about 25 projects, investigates the integrity of drilled shafts in a way that’s di erent and more economically advantageous, says Beim. “ e traditional, current way of testing drilled shafts to see if they’re adequate or not is by doing crosshole sonic logging. Crosshole is a very good test, but it has two disadvantages: One is you have to wait for the concrete to cure in order to perform the test, so you’re waiting a week or so. e second is that you don’t really see the entire cross-section of the drilled shaft. You can’t see everything that is on the outside of the reinforcement cage.” TIP remedies this by measuring the heat generated by the curing concrete which gives a more complete picture. “Because the data is taken while the concrete is curing, you’re doing the test 24 to 48 hours after construction of the foundation element and getting answers right away so you can move on with the building process much faster…We see a lot potential in this product.” (See ad on page 31.) Economic pressures in 2011 continue to force companies to re-think markets, processes, reasonable fee structures, products and more. With continued uncertainty in global and U.S. economics, success appears to come from an ability to be nimble and adapt businesses to these events and emerging trends.▪
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