Deformation Mechanism of Hardened Cement Paste and Effect of Water

Triaxial compressive tests were conducted at different confining pressures (Pc) and water contents to understand the deformation mechanism of hardened cement paste (HCP). Results showed that the stress did not decrease up to 10% strain and macroscopic damage was not observed when P-c was higher than a certain value. P-c required for this ductile behavior differed depending on the HCP water content. Stepwise creep tests were also conducted. Most of the slopes of the obtained differential stress-strain rate curves in the double logarithmic chart were approximately three, which indicates that dislocation creep was the dominant deformation mechanism. The samples saturated with sucrose solution exhibited a more brittle behavior after the peak stress than those saturated with tap water. The different behavior in the softening region was attributed to calcium hydroxide precipitation because it was suppressed in the sucrose solution. These results indicated that the HCP deformation may be affected by dislocation, mechanical twinning, and pressure solution.