New Experimental Method for Studying Early-Age Cracking of Cement-Based Materials

In this paper, a novel ellipse ring apparatus and its application for testing early-age cracking in restrained cement-based materials are presented. This method can accelerate crack propagation of cement-based materials and automatically record the starting point of a crack. Using this method, the effects of different kinds and contents of alkali on early-age shrinkage and cracking of cement-based materials have been investigated. The experimental results have shown that the cracking sensitivity of mortar with high alkalinity is more notable than that of plain mortar. The mechanism of such a behavior is further investigated using electrical resistivity measurement and hydration heat measurement.