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ASTM standard defines specifications for 'green' concrete mix design.
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As a producer, I would like to learn more about adding silica fume to my mix. What are its effects and where can I get more information?
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Our county water department recently announced plans to build a new facility. This high-profile project would be the perfect opportunity to present the advantages of a performance-based mix design. What are some of the aspects we should focus on? How should we tout the benefits of performance-based...
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Q. We are about to begin a large project that will require our technicians to take hourly field test samples of the fine materials. We’ve started to investigate alternatives to our normal oven-drying procedures. One method we recently discovered is vacuum drying. Do you know anything about this...
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Compressive strength is one of the most important measurements in manufacturing concrete. As a producer, I need to know whether this measurement is accurate. How can I be sure my concrete compressive strength results are correct?
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We recently won the bid to supply a large project. The good news is that there’s a large volume of concrete; the bad news is that the engineer has called for all of the measurements to be in metric. Converting our batching system to metric is a breeze, as the software supplier has provided an...
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We make precast septic tanks and often get water trails on the tank surfaces, even though we use admixtures. Is there a way to avoid these, or will they always have some trails?
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We have started having problems with variations in air content of our air-entrained mix designs. Air content stays uniform for a while, then goes out of the specification range. Usually, measured air content is too low, but sometimes we get exceptionally high values. I know that many factors affect...
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We’ve been asked to bid on an upcoming concrete bridge deck. The project requires a hardened concrete that will resist corrosion. Normally on jobs like this we recommend micro-silica. But in this case, there’s a catch. The bridge is part of a high-profile project that features decorative concrete...
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I am a concrete producer in the Upper Midwest and always must adjust my product for very hot weather conditions in the summer and cold temperatures in the winter. What advice do you have for producers like me who must figure how cool to make our aggregate in extreme weather conditions?To answer...
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I’ve heard that ACI may soon be offering a certification program for competency in concrete design. Does this have anything to do with NRMCA’s P2P and the move toward performance specifications? And what can you tell me about the certification program?
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More of our customers are starting to ask us about the possibility of using self-consolidating concrete. What’s going on with the development of standardized tests for SCC?
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Are there general guidelines for cutting through prestressed precast concrete? A local church wants to install an elevator, which would mean cutting an existing elevated precast concrete hollow core floor. They asked us for advice, but we don’t have any experience with structural precast.
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As a producer, how can I use the recent changes in ASTM standards to use process water in my concrete? Promoting using process water in concrete is a tedious effort. We turned to three experts to answer this important question. The answer below is supplied by Richard S. Szecsy, PhD, PE, vice...
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What can we tell our contractor-customers who insist on a low water-cement ratio but who then complain the concrete is hard to finish?
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One of our customers wants to cut construction time on a job that will include several concrete retaining walls. They’ve asked us how quickly they can backfill these walls and how much sooner they can do that if they use a high early-strength mix. What should we tell them?
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What are the most effective products to clean and to seal the older type slump block. I’m working on a 1977 vintage slump block home.