Material Compatibility Issues Addressed in New Concrete Standard
The realization that concrete production is the result of a combination of several materials that are individually standardized, but which may interact in ways not governed by those standards, led ASTM International Committee C09 on Concrete and Concrete Aggregates to form Subcommittee C09.48 on Performance of Cementitious Materials and Admixture Combinations in 2004. The subcommittee has now completed its first standard, the recently approved C1679, Practice for Measuring Hydration Kinetics of Hydraulic Cementitious Mixtures Using Isothermal Calorimetry.
According to Paul J. Sandberg, principal scientist, W.R. Grace, and chair of the task group that developed C1679, the first order of business for C09.48 was to define practices for investigating the interactions of materials used in the production of concrete. “While ultimately the subcommittee may focus on ways of changing our material standards to reflect the need for compatibility, the first step was to define practices for investigating such interactions. Incompatibility issues are becoming increasingly common in the concrete industry as concrete producers are faced with a wider variety of admixtures and increasing amounts of supplementary materials as a way to reduce cost and, more recently, to reduce the carbon dioxide footprint of concrete,” says Sandberg. “Accordingly, methods to investigate how materials work together, not individually, are needed.” Sandberg notes that isothermal calorimetry was the first method addressed by C09.48 because it provides a convenient way to track the hydration reactions affected by interactions of cements, supplementary materials and admixtures.
C1679 is a practice for studying the reactivity or hydration kinetics of a binder system in any combination with other materials that can be done at different temperatures and mixing conditions. The standard will be useful in a variety of applications for producers of concrete, cement, admixtures and supplementary materials, as well as for testing laboratories and contractors, particularly in determining how products interact with other materials and selecting materials whose combination in a given concrete mix is the most suitable for its intended application.
Sandberg says that interested parties from the various industries involved in concrete production are welcome to join in the standards developing activities of C09.48. “Since C1679 is the first standard of its kind, dealing with the potential lack of compatibility of materials that all by themselves are covered by standards specific to each material, there will be many issues and needs for revisions to come.”
Technical Information: Paul J. Sandberg, W.R. Grace, Cambridge, Mass.
ASTM Staff: W. Scott Orthey