Cracking due to leaching in cementitious composites: Experimental investigation by means of X-ray microtomography and numerical modeling

Chemical degradation of cement based materials leads to significant degradation of their physical properties. A typical scenario is a calcium leaching due to water (water with very low pH compared with that of porous interstitial fluid). The main objective of this paper is to evaluate the evolution of microstructure induced by leaching of a cementitious composite using synchrotron X-ray microtomography, in the particular way of identification of cracking induced by leaching. After a brief description of the degradation mechanism and the X-ray synchrotron microtomographic analysis, we propose a numerical simulation performed in order to prove that cracking due to leaching is induced by an initial pre-stressing of concrete. This pre-stressing is due to endogenous shrinkage. After leaching, the tensile strength of cement paste is dramatically reduced leading to microcracking.