Test Methods for Rapid-Hardening Magnesium Phosphate-Based Cements

Abstract

Abstract This paper describes several different test methods that were used for rapid-hardening cements. The term “rapid-hardening cement” is defined in this paper as a hydraulic binder that can develop at least 2000-psi (15-MPa) compressive strength within 2 h under normal conditions. Due to the special nature of these cements, it is questionable whether the conventional methods are suitable for testing them. The quickness of setting and the very rapid strength development may cause a need for special testing procedures. Furthermore, unlike the standard portland cements, these materials come as a mixture of sand and cement. The conclusion is that many of the applied ASTM methods, perhaps with modifications, can provide useful information about the technically important properties of these rapid-hardening cements. This paves the way toward a more uniform testing and the eventual standardization of test methods for these special cements and mortars of increasing popularity. Though this paper describes only magnesium phosphate (MP)-based cements, the conclusions of the paper apply to most of the rapid-hardening hydraulic binders.