Thermal Impact on the Physical and Transfer Properties of Slag Cement and Portland Cement Concretes

The cement industry confronts significant environmental challenges, primarily due to extensive raw material and energy consumption, and consequential substantial greenhouse gas emissions such as carbon dioxide. Escalating energy expenses and stringent environmental regulations mandate the reduction of industrial emissions through the incorporation of industrial by-products like blast furnace slag. In this study, a comparative analysis was conducted to evaluate the physical and transport properties of concrete made with slag cement versus that made with Portland cement, particularly after exposure to high-temperature conditions. Specimens, cured for 90 days at 20 degrees C in water, underwent a series of four heating-cooling cycles at incremental temperatures of 160, 300, 400, and 650 degrees C, with a consistent heating rate of 1 degrees C/min. Various durability indicators, including mass loss, water-accessible porosity, gas permeability, capillary water absorption coefficient, and chloride ion apparent diffusion coefficient, were measured. It was observed that an increase in the temperature of exposure led to a reduction in weight, porosity, permeability, diffusivity, and capillary water absorption in both concrete types. Notably, the slag cement concrete exhibited marginally superior durability parameters compared to the Portland cement concrete, with the exception of porosity. Empirical correlations derived from the experimental data between porosity, water absorption, and gas permeability facilitate the assessment of the apparent diffusion coefficient in fire-damaged concrete incorporating blast furnace slag, up to a temperature of 650 degrees C.