The effect of pressure on tricalcium silicate hydration at different temperatures and in the presence of retarding additives

The hydration of tricalcium silicate (C3S) is accelerated by pressure. However, the extent to which temperature and/or cement additives modify this effect is largely unknown. Time-resolved synchrotron powder diffraction has been used to study cement hydration as a function of pressure at different temperatures in the absence of additives, and at selected temperatures in the presence of retarding agents. The magnitudes of the apparent activation volumes for C3S hydration increased with the addition of the retarders sucrose, maltodextrin, aminotri(methylenephosphonic acid) and an AMPS copolymer. Pressure was found to retard the formation of Jaffeite relative to the degree of C3S hydration in high temperature experiments. For one cement slurry studied without additives, the apparent activation volume for C3S hydration remained close to similar to-28 cm(3) mol(-1) over the range 25 to 60 degrees C. For another slurry, there were possible signs of a decrease in magnitude at the lowest temperature examined. (C) 2012 Elsevier Ltd. All rights reserved.