Granulated Blast Furnace Slag as a Supplement Enhancing Fire Resistance of Portland Cement Mortar

Abstract

Using steel slag in the cement industry has been considered a green recycling solution to the solid waste problem. Granulated blast furnace slag (GBFS), in fact, is used as an additive to counteract the sulfate attack of Portland cement; however, its ability to undergo fire or heat exposure has not been highlighted yet. Therefore, this study focuses on compressive strength behaviour at high temperature along with workability of cement paste of cement containing GBFS. Here, a set of blended mixture prepared with OPC was replaced by GBFS at 10, 20, 30, 40 wt.%. Setting time of pure OPC and blended OPC and GBFS was carried out to evaluate workability of all mixtures. After 28 days of curing, compressive strength of samples exposed to heat at 200, 400 and 600 °C was measured. Along with that, the mass loss of the sample to predict thermal resistance was analyzed by thermogravimetric analysis (TGA); moreover, microstructure of hardened samples in terms of mineral composition, distribution was analyzed by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). Results of the conducted study showed that GBFS addition into OPC could enhance fire resistance through the slight increase in compressive strength compared to the OPC one at 600 °C and the mass loss; moreover, the blended cement containing different amount of GBFS maintain workability of cement paste.