Impact of High Temperature on Residual Properties of Concrete with Steel Slag Aggregate

Abstract

This study evaluates how elevated temperatures can affect the properties of concrete prepared with steel slag as a coarse aggregate. Four slag-based concrete mixtures were studied, using different types of cement pastes prepared with portland cement, fly ash as a 20% replacement of portland cement, and polypropylene fibers at 0.1% by volume, respectively; an additional dolomite-based reference mixture with portland cement served as a reference mixture. The test samples, which were prepared and aged for 56 days, were subjected to temperatures from 100 to 800°C. The residual mechanical properties of the cooled samples (i.e., their compressive strength and static modulus of elasticity), as well as their weight loss and residual ultrasonic pulse velocity, were determined and compared with those of the reference concrete. Additionally, scanning electron microscope analysis of the concretes and dilatometrical analysis of the cement pastes and aggregates were performed. The obtained results showed that the residual properties of concretes made with steel slag aggregate were comparable to those of the reference dolomite concrete up to a temperature of 600°C, whereas at higher temperatures, the slag exhibited expansion, which negatively affected the residual properties of the slag-based concrete mixtures.