Q. The last few seasons we've had difficulty controlling our water demand and our yields due to the sand's variability in absorption and specific gravity. Our quality control problem is compounded because our stockpile area is rather small. So by the time the lab sends us the sample results, the...
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Q. In the past few years, we have noticed that mix design specifications have become more complex. Many documents contain terms such as admixtures, additives, and agents. What is the difference in these terms?
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Q. We are bidding on a large school project that is planned to be a LEED-certified structure. The architect has asked if we can supply a concrete masonry unit (CMU) that could be cast with supplementary materials to help qualify for LEED points. Are there any guidelines?
Q. We are involved in a quality claim in which the testing lab reports the hardened concrete did not achieve the specified design strength. Our testing lab broke cylinders from that same job and all achieved proper strength. We are confident that we will achieve proper strength if the coring is...
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Q. We are in the early planning stage of a major commercial project. During site preparation, the general contractor will require us to demolish and crush a large quantity of existing concrete used in the structure and pavement. In fact, looking through our records, it appears we supplied the...
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Q. We have just equipped several of our mixers with an on-board slump monitoring system. As the truck travels to or waits at the jobsite, the system monitors the mix's slump. When the system's controller senses a significant stiffening of the mix, it will maintain the load's targeted slump by...
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Q: We plan to bid on some state bridge deck work planned in our area. Our district engineer is open to allowing a high-performance mix that will help mitigate the possibility of undue cracking. Our lab is analyzing several mixes with standard features such as strength, set time, and chloride...
We are involved in a dispute on the quality of a decorative slab for which we supplied concrete last fall. The project appears to be fine, but one set of test cylinders failed to meet compressive strength requirements.
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Members of ASTM Subcommittee C9.49 are attempting to standardize the testing methods for pervious concrete. There is much interest in this topic, as committee secretary Jenny Hitch reports more than 120 people are members of this committee, making this one of the largest groups in C-9.
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We recently supplied several split-face blocks for a large commercial project. The work continued for several months, and with about two weeks left, we started receiving complaints about the quality of the units from the mason contractor.
Q: I'm fairly new in the concrete business and I know that a mix's water-cement ratio affects how well the concrete turns out. But why should I also care about something called "aggregate moisture," and what is it?
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The Portland Cement Association's (PCA) National Standards Development Committee has approved the first PCA standard utilizing the American National Standards Institute (ANSI) accredited voluntary consensus process.
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Q: Our lab has developed a self-consolidating concrete (SCC) mix design that we plan to use on a recently awarded project. It will be our first large SCC project. While we have provided the SCC recipe on several small jobs and for this project's test pours, this will be our first attempt to...