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A proposed ASTM standard could help ready-mixed producers, contractors, and testing firms pinpoint the source of fresh concrete problems in increasingly complex mixtures.

ASTM subcommittees are developing new concrete-related standards for material suppliers and design/construction professionals. Under the auspices of Committee C09 on Concrete and Concrete Aggregates (which next meets in Atlanta, Ga., in December), four proposed standards are underway, one spearheaded by a University of Toronto professor.

R. Doug Hooton, PhD, P.Eng., chairs Subcommittee C09.48 (performance of cementitious materials and admixture combinations). He says the proposed ASTM WK 23967, Practice for Measuring Hydration Kinetics of Hydraulic Cementitious Mixtures Using Semi-adiabatic Calorimetry, provides guidelines on the use of thermal measurements of hydrating cementitious mixtures to evaluate behaviour of concrete mixtures and assess types of abnormal performance.

Hooton believes this should help ready-mixed concrete producers, contractors, and testing firms pinpoint the source of fresh concrete problems in increasingly complex mixtures. Semi-adiabatic calorimetry can also be employed to help prevent future problems as materials properties, mixture proportions, and placing temperatures change.

"While concrete is a very versatile material and works very well in the vast majority of cases, with more complex combinations and proportions of materials being used to produce more sophisticated concrete, problems can occasionally occur onsite when the material is delivered or handled," Hooton told Construction Canada Online.

"The biggest practical problems for suppliers and contractors are those associated with a concrete that does not have or maintain the required workability, or does not set as expected. Sometimes that occurs due to the wrong concrete being ordered for the job, but in other cases—for example, in extreme hot or cold weather—something unexpected might happen on occasion with concrete that performs well at normal temperatures," he continued. "The purpose of this potential new standard is to provide a tool to help both material suppliers and concrete producers predict whether there is potential for a problem, if the 'envelope' gets pushed."

Other potential new concrete standards could also prove very beneficial to design/construction professionals with respect to aggregate resistivity, lightweight aggregates, and methacrylate bonding systems. For more information, visit the committee website and seek out ASTM WK 24621, 23421, and 24405.