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Quality control of expansive concrete using a thin cylindrical steel mold

by Masato Tsujino, Hiroshi Hashida, Ryuki Yuasa and Toshifumi Kikuchi

Expansive additive is increasingly being used to reduce the cracking that results when concrete shrinks. Although appendix 2 of JIS A 6202 specifies a method for evaluating the restrained expansion of concrete mixed with an expansive additive, this method is not simple and is used only for limited evaluations. A new method was required for controlling the quality of the expansion effect in concrete mixed with an expansive additive and used for actual structures. We developed a simple r restrained expansion test method that applies the thin cylindrical steel mold used for the compressive strength test. This thin cylindrical steel mold method can be used to determine the amount of the initial expansion of concrete containing various amounts of an expansive additive. The amount of expansive additive added to the concrete is used to accurately determine the amount of expansion up to about 40 kg/m3. Moreover, the method is a modification of the restrained expansion in the former JIS A testing method, describes a nearly perfect proportional relationship, and clearly shows nearly equal expansion strain for materials that have been aged for seven days. Furthermore, the expansion of expansive concrete can be evaluated and the results used for quality control by selecting the optimal strain gauge according to the temperature or type of concrete.