Effect of supplementary cementitious materials on the resistance of cement paste to carbonic acid water

摘要

Cement pastes blended with fly ash or slag suffering from carbonic acid water were investigated. Thermogravimetric analysis was performed to determine the effect of fly ash and slag on CH content in cement pastes. Mercury intrusion porosimetry was used to characterize the effect of fly ash and slag on pore structure of cement pastes. Decalcification shrinkage and corrosion depth were determined to characterize the deterioration of cement paste after corrosion. The results show that the decalcification shrinkage is related to the initial CaO content and the composition of CSH gel. The corrosion depth depends on its initial CH content and pore structure. The results show that the paste blended with both fly ash and slag has good resistance to carbonic acid water in terms of decalcification shrinkage (reduced by nearly one half compared by the largest one) together with corrosion depth (reduced by nearly one third compared by the largest one). Furthermore, H2CO3 diffusion coefficient of the paste as a function of time was determined, which can be used to predict the durability of the pastes.