Papers by Author: Cai Jun Shi

Abstract: In this project, a process was developed to cure concrete masonry blocks using CO2. It was found that the strength of concrete mixtures for block manufacture after CO2 curing was close to that after conventional steam curing. A dry pre-conditioning before CO2 curing was very critical to achieve high degree of CO2 curing. The specimen pre-conditioned in the moist environment hydrates more than those pre-conditioned in the dry environment during the pre-conditioning period. However, much less CaCO3 formed in the former that that in the latter after the CO2 curing. Thus, the CO2 curing is mainly contributed by the reactions between CO2 gas and cement clink minerals.

Abstract: Hardened cement paste and concrete are porous materials. Most engineering properties of hardened cement pastes and concrete, such as strength, shrinkage, permeability, etc., are influenced or controlled by their pore structure characteristics. The ingress of chloride ion into concrete can cause steel corrosion and damage of steel reinforced concrete structure. This paper reviews the pore structure characteristics and transport mechanisms of chloride ion, such as hydrostatic advection, capillary suction, diffusion, thermal migration and electrical migration, in hardened cement pastes and concrete.