Contributed by Chris Maskell
Is there a problem with flooring glued to concrete with a high fly ash content? Fly ash is the finely divided residue that results from the combustion of ground or powdered coal and that is transported by flue gasses. It is used as a replacement for Portland cement in concrete and in some cases can add to the final strength, increase its chemical resistance and durability and can significantly improve the workability of concrete.
If you talk to enough flooring professionals on the subject of site preparation and related issues, eventually the question of concrete, high fly ash content and adhesive bond failure will crop up.
I've heard the question from all corners of the commercial flooring industry, and there are many concerns, but few definitive answers. As a result, many commercial flooring contractors are not warrantying their installations over such concrete. Instead, they add a disclaimer in their 'terms and conditions’ stating that no installation warranty is offered when a certain percentage level of fly ash in the concrete mix is exceeded. Some say 15%, others 20 to 25%, some say more. Such disclaimers won't protect the flooring contractor if there is a failure and things turn nasty.
Concrete with a high fly ash content results in a denser, less porous product. This in turn can interfere with the flooring adhesive’s (or hydraulic cement underlayment's) ability to mechanically bond. Hard troweling of the concrete surface to a super smooth finish adds to the problem, and introduces the need for shot blasting. Shot blasting requires time and money, both of which are in short supply at the end of the project when the flooring is scheduled.
As concrete mixes are proprietary to the concrete supplier, it can be difficult to confirm exactly how much fly ash is present in any one mix. If this is the case or where the concrete is super smooth, unusual in color, or if you are just not sure, then perform a water absorbency test in accordance with ASTM F-3191 and/or a bond test prior to installation.
Place dime sized droplets of water on the cleaned concrete surface, if they are not absorbed after 60 seconds (or in accordance with ASTM F-3191), you could be facing an adhesive bond issue. If this is the case then you need to shot blast to a concrete surface profile (CSP) of 1 or 2, or per adhesive manufacturers’ requirements depending on the floor covering to be installed. (A CSP 2 for example, is similar to 60 grit sandpaper)
Contributed by Chris Maskell
The flooring industry is constantly challenged by the same repeating issues. Installing too early, wet concrete, non-flat sub-floors, sub-floor surface not prepared, heat not on, windows not in and lack of installer training and certification. In fact, as construction speeds up to meet demands for faster build times and with the threat of an increase in the cost of borrowing money lurking in the economic wings, the provision of acceptable conditions for the flooring contractor is becoming less likely.
This raises the importance of supporting those in the construction team (Building Owner, Construction Manager, General Contractor, Design Authority, and Flooring Contractor) with good, timely information that helps all involved plan ahead for the floor covering installation. As one of the last significant trades onsite, the flooring contractor needs certain conditions, that if not planned for in advance, will be next to impossible for the Construction Manager/General Contractor to provide without extra time and/or extra money: two things in short supply at the end of a build or renovation.
Change is possible, but requires a few things to be understood and acted on in advance.
There is a generic Canadian floor covering industry reference manual available for specification, which supports all construction parties, and when included in the Division 09 section of the construction documents, means correct flooring processes and supportive language is available to guide the floor installation and all the points listed below.
Contributed by Jason Spangler
For years now, the in situ relative humidity (RH) test for measuring the moisture condition of concrete has been shown to be the most reliable, accurate test available.
As far back as the 1960s, laboratories at the Portland Cement Association conducted controlled tests that verified the accuracy of RH testing. This research was followed by years of additional testing at Lund University in Sweden and elsewhere. In 2002, ASTM International first established the F2170 standard for conducting RH tests on concrete slabs.
The research confirmed two key discoveries:
Other methods typically involve taking measurements only at the surface of the slab. As the research has found, a surface-based moisture test can’t provide an accurate measure of a slab’s true moisture condition. That’s because it doesn’t account for the moisture conditions deeper within the slab, and those conditions are typically quite different than conditions at the surface.
The Standard Evolves as the Science Tells Us More
The initial ASTM F2170 for in situ RH testing was established in 2002, after continuing research at Scandinavian universities in the 1990s identified the exact specifications for conducting a reliably accurate RH test—placing the test probe at 40 percent depth for slabs poured on grade or 20 percent for slabs drying from both sides. After these scientifically-validated specifications were firmly established, ASTM International published a usable standard.
Until now, the ASTM F2170 standard has required a 72-hour waiting period between drilling the test holes where the RH probes are placed and taking official RH measurements. In practice, readings are often taken before the 72 hours has passed, so contractors have an idea of how things are trending. But because the official readings couldn’t be taken before 72 hours, that meant all decisions and work were basically on hold for those three days. Full stop.
Yet we’ve seen how the research on the RH test method has helped to refine our understanding of how best to use it. This trend continues. In 2014, a Precision and Bias (P&B) study, commissioned by the ASTM committee, tested for differences in RH readings at various intervals within the 72-hour period. In part, the idea was to assess if it is actually necessary to wait the full 72 hours for an accurate, actionable moisture readings.
Contributed by Eric D. Lussier
The space is enclosed, the HVAC is running and the basketball backboards are in place. The final touch to your athletic facility is the only item outstanding: the sports floor. You have made your selection and the contractor is scheduled. All you need to worry about is the completed installation, right? Well, have you put thought into periodic maintenance? You always want your facility to look clean and new, but some floors take more work than others. The following provides insights into the various finish options and upkeep factors that must be considered when it comes to choosing from among the many athletic surface options.
It seems ridiculous to start the overview with what could seem like no flooring at all, but due to its lifespan and durability, concrete remains a choice in the athletic flooring market. If you are building a new facility, chances are concrete serves as your base substrate regardless of what floor surface is specified. And, whether it is intended for team or individual sports, or for multipurpose use, chances are those activities can occur on a concrete surface.
The downside of a concrete surface, however, is the safety factor. While a player may not think twice about shooting hoops on an outdoor concrete basketball court, that same person would likely be apprehensive about lacing up their high tops on an indoor concrete court. Why? Because concrete doesn’t offer any sporting characteristics, such as force reduction, also known as shock absorption. ASTM F2569, Standard Test Method for Evaluating the Force Reduction Properties of Surfaces for Athletic Usability, defines force reduction as the “ability of a surface to reduce impact forces as compared to a rigid surface using a specified impact.” Concrete on its own offers no force reduction.
ASTM F2569 was repackaged in the official sports flooring standard: ASTM F2772, Standard Specification for Athletic Performance Properties of Indoor Sports Floor Systems. In 2009, additional criteria were added for surface finish effect, which is the slip and grip of a floor, known as coefficient of friction.
Nevertheless, if team or court games will be played on a concrete surface, one important finish application is game lines. Pay attention to the coating used to mark lines on any athletic flooring, as heavy foot traffic and cleaning equipment can take a toll on the paint used. Typically, a polyurethane-based coating with a hardening catalyst is specified for longevity reasons.
The concrete surface may also receive a stain or a polish before usage. With these kinds of finishes, high-traffic areas will require upkeep much sooner than low-traffic areas, but one can expect to refinish the surface anywhere from five to 20 years, depending on usage.
Contributed by Matt Porta
As we put 2016 to bed and kick off 2017, the need to rise above, stay positive, and the need to pursue excellence seems even more important than ever. Today's post is step one of my perspective and attempt to articulate in writing what I hope to accomplish with my firm, Hord Coplan Macht, in 2017. My goal is for this post to be one of a regular series, each building upon the previous.
Some time around 2003 we started to see a shift in the overall project schedule here in Colorado. For me, it was with the design and construction of the Excel Academy Charter School. It was a new school building for an established charter school in Arvada, CO. We were hired, along with our construction partner, Saunders Construction, in the fall. The goal was to design, permit, and construct a new 44,000 square foot school building on a five acre site in time for the 2004 school year. The SLATERPAULL design team geared up, worked side by side with Saunders and completed construction drawings before Christmas, broke ground in January and were complete in August. We were able to construct a very unique solution, outside of the gymnasium, and there is barely a single right angle in the building. The project won a tilt-up concrete construction award and began the basis of the new normal as it relates to the design and construction schedule.
Success begets opportunity and this same design and construction team was selected by the Jefferson County School District to build a new 63,000 elementary school, the first new school of their successful 2004 bond election. We interviewed and were selected in January of 2005, started design immediately, completed phased construction documents, with the site drawings issued in April and the building in June. Construction began in May and the school was completed by August of 2006. This new school, again a tilt-up concrete award winner, became the new benchmark for new public school design and construction and hence the official start of the new normal, where every bond funded school project in Colorado seems to follow.
What I have learned in our fast paced design and construction world is that expectations for excellence by our owners have not changed. A process that used to be scheduled over 30 months is now completed in 18. The biggest concern I have personally and professionally with this level of schedule acceleration is maintaining quality. Quality of our designs, quality of our details, quality of the overall coordination of our documents and the overall quality of construction.
So, if am worried about quality, what do I propose we do about it...
Stay tuned for part two.
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