Water vapor sorption of cement pastes altered by temperature and carbonation

Abstract

This paper endeavors to clarify the impact of temperature and carbonation on the water vapor sorption isotherms (WVSI) of hardened cement pastes, in view of applying the laboratory measurements to real environments. Incorporating different supplementary cementitious materials creates distinct pore structure features: adding 30% fly ash at w/b of 0.4 generates more capillary pores and confined macropores, while 50% slag incorporation refines the ink-bottle necks. Carbonation of CH decreases mesopores but increases macropores, and the clogging of cavitation-controlling pores only occurs as C-S-H is substantially carbonated. Elevated temperatures will mobilize part of the interlayer water and remove it in high RH range before cavitation, mitigate pore blocking, shift cavitation-related drop, but have minor impact on the physisorption. Particularly, the thermal dependence of cavitation is quantified with experimental results and molecular dynamics simulations.