Short‐Time Creep Transition for Hardened Cement Paste

Abstract

Short‐time creep recovery tests in two‐point bending were performed on hardened cement paste beams water‐cured at #100° and 25°C. The experimental variables were pore structure, equilibrium moisture content, and temperature. The recovery curves were analyzed using linear viscoelastic concepts, which revealed a transition in the time range 0.2 to 10s which is both linear with stress and reproducible. A lognormal distribution of retardation times characterizes the transition. It is tentatively proposed that internal redistribution of capillary water is responsible for the transition. Experimental observations which support this view are: (1) The size of the transition increases with increasing amounts of capillary water for saturated pastes; (2) the transition strength decreases greatly when the capillary water is removed; (3) the apparent activation energy of the transition (3.8 kcal/mol) agrees well with that for viscous flow of water.