ASTM International Committee C01 on Cement and Committee C09 on Concrete and Concrete Aggregates have joined forces to form a new subcommittee, C09.48/C01.48 on Performance of Cementitious Materials and Admixture Combinations. The scope of the new subcommittee is to develop and maintain standards for investigating interactions and evaluating changes in early-age properties when various combinations of hydraulic cements, supplementary cementitious materials, other finely divided materials, water and chemical admixtures are used in cementitious mixtures.

The subcommittee, which began as a task group of the executive subcommittees for Committees C01 and C09, started as an effort to deal with problems that occasionally arose when fresh concrete was produced with hydraulic cement, pozzolans, and chemical admixtures.

According to Doug Hooton, professor of civil engineering at the University of Toronto and a former chair of Committee C09, some of these problems include lack of or excess workability, premature loss of workability, premature or delayed setting (hardening), and problems with controlling entrained air. Combinations of hydraulic cement, pozzolans and chemical admixtures, changes in the proportions of these materials, or in the composition of any of the ingredients, or a change in temperature can all be triggers for these problems.

"The goal of this subcommittee is to develop easy or rapid small scale tests or standard practices that can be used to predict the potential for such problems in advance, and which can also be used to develop solutions before the concrete is mixed commercially," says Hooton. "This has the potential to save the industry money in rejected concrete or concrete that has to be removed."

Subcommittee C09.48/C01.48 will meet during the December ASTM International Committee Week in Dallas, Texas.

For further technical information, contact Dale Bentz, Building and Fire Research Laboratory, National Institute of Standards and Technology, Gaithersburg, Md. (phone: 301/975-5865; dale.bentz@nist.gov). Committee C01 meets Dec. 7-9, in Dallas, Texas. For membership or meeting details, contact Jim Olshefsky, ASTM International (phone: 610/832-9714; jolshefs@astm.org).