Problem Clinic

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    Correcting for Aggregate Moisture

    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?

     
  • Standard Test Method for Density, Yield and Air Content

     
  • New Concrete Wall Standards

    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.

     
  • Preparing for an SCC Job

    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...

     
  • Reducing Formwork Pressure for SCC

    We are urging an engineer to specify self-consolidating concrete (SCC) on a project that includes several tall, vertical forms. The engineer recognizes the benefits of SCC regarding consolidation and final surface appearance. The contractor also wants to use SCC because it can speed up the pouring...

     
  • SCC Concrete Formwork Pressure Study; New Approved ASTM Standards

    A Progress Report and Task 1 Report for the Self-Consolidating Concrete Formwork Pressure Study are now available, and the latest on recently revised ASTM standards.

     
  • Retaining Wall Block Durability

    We have been trying to convince our local public works officials to specify segmental retaining wall (SRW) blocks on an upcoming project. We are located in the northern part of the United States. And the county's engineering staff is concerned that the SRW blocks will not be durable given our...

     
  • ASTM to Develop Green Roof Guide

    A proposed new ASTM International standard, WK14283, "Guide for Green Roof Systems," will identify terminology, principles, and concepts for building vegetated green roof systems.

     
  • Does Well-graded Aggregate Stand Up?

    Q: We are beginning to work on a new set of mix designs for a large commercial project. We are experimenting with some potential changes in the aggregate gradations of our commonly used products.

     
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    Hot Weather Concrete Practices

     
  • Putting Aggregate to the Test

    We are being forced to look for a new source of coarse aggregate. The problem is our choices are limited. One of our options, and it appears our most economical one, will be from a quarry whose aggregate is known to be susceptible to alkali-silica reactivity.

     
  • New Approved ASTM Standards

     
  • Problem Clinic: Green Sources

    Q. We are interested in learning more on how to participate in the green building movement. We are particularly interested in finding out about any standards on products and systems. Where can we start?

     
  • Spec Watch

    Several important ASTM standards affecting concrete producers have been updated. This list summarizes some committee announcements recently released.

     
  • Problem Clinic: Concrete on Ice

    Maintaining the temperature of concrete.

     
  • New ASTM Work Items

     
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    Strength Testing Woes

    Concrete strength testing is a much larger problem for ready-mix producers than many in the industry realize.

     
  • Spec Watch

    Possible New SCC Field Test

     
  • Stripping Product

    To avoid problems stripping product, be sure the form is in good conditon.

     
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    Controlling Shrinkage

    Many factors influence shrinking and curling of concrete floors.

     
 
 
 
 

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