Water attack of a cement paste: towards an improved accelerated test?

In recent years much work has been undertaken to try to understand the mechanical effects of leaching by water on cement paste. One of the major problems is the kinetics of the degradation, which is too slow to allow observation of any significant mechanical effects during the time frame of an experiment. This study attempts to compare the chemical and mechanical results of the migration test on an ordinary Portland cement paste with those from the flowing water test on a C₃S hydrated paste. Cracks are only observed with the migration test, and seem to be caused by the structural transformation associated with the Ca/Si decrease in C-S-H or by silica gel precipitation.