PORE WATER POTENTIAL DEVELOPMENT IN CEMENT-BASED MATERIALS

Abstract

Consumption of water during hydration reactions and surface water evaporation result in the development of negative pressure in capillary pores of concrete at early ages. Capillary pore water potential (PWP) creates early-age shrinkage strain and increases the chance of early-age cracking. The aim of this study was to investigate the effects of internal curing (IC) and water-to-cementitious materials ratio (W/CMs) on the hydration reactions and PWP development in cement-based materials. For this purpose, 11 mortar mixtures with different W/CMs (0.3, 0.375, 0.45 and 0.525) and lightweight fine aggregate (LWFA) substitutions (10, 20, 30 and 50%), as well as, 9 concrete mixtures with different W/CMs (0.35, 0.42 and 0.5) and LWFA substitutions (10, 20, 30 and 40%) were made and evaluated through isothermal calorimetry and pore water potential tests. The results demonstrate that IC is efficient in both promoting hydration kinetics and suppressing capillary PWP development, especially for the mixtures with low W/CMs.