Problem Clinic

  • What is Cellular Concrete?

    Q. With the price of asphalt rising despite lower crude oil prices, a contractor told us he may enter theroofing business by providing cellular concrete. What is cellular concrete? Can it be made in a concrete plant?

     
  • Pricing Pervious Concrete

    TCP blogger Matt Offenburg answers the question: “Is a yard of pervious concrete a yard?” and “Should pervious concrete be bought and sold by the cubic yard?”

     
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    Minimizing Gradation Testing Variability

    It seems that many of the field labs had performed gradation tests with worn sieves. While most differences were minor, they introduced a degree of unnecessary variability when combined. How can we can minimize our testing variables on these large projects?

     
  • Quality Control for Pervious Concrete

     
  • Updated Epoxy-Coated Rebar Specifications Brochure Now Available

     
  • New ASTM Initiative Supports Sustainability

     
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    Faster Testing for Fine Aggregrate Quality

    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...

     
  • Cement and Concrete Reference Laboratory Announces Two New Calibration Standards

     
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    Admixture or Additive?

    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?

     
  • Casting a Green Block

    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?

     
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    Proper Coring Techniques

    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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    What 318-08 Means to Producers

     
  • Updates on High-Performance Concrete

     
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    Pre-Tensioning Steel Forms

     
  • Recycled Aggregate for Structural Concrete

    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...

     
  • Reporting Tempering Water

    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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    Surface Crazing

     
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    Impossible Color Requirements

     
  • Testing for Bridge Deck Shrinkage

    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...

     
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    Decorative Slab Core Samples

    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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