Phase transformations and mechanical strength of OPC/Slag pastes submitted to high temperatures

Ground granulated blast furnace slag (GGBFS or slag) is a by product of the steel industry and is often used in combination with ordinary Portland cement (OPC) as a binder in concrete. When concrete is exposed to high temperatures, physical and chemical transformations lead to significant loss of mechanical strength. Past studies have reported changes in concrete where OPC is 100% of the binder, but there is a lack of published data on slag blended cements. This work provides better understanding of how slag blended cement pastes behave when exposed to high temperatures, when the critical transformations occur, and what the consequences in the structure of these pastes are. Thermogravimetric analysis made it possible to identify when the transformations occurred and the changes in mechanical strength in the cement paste. A unique outcome of this work is the lower damage presented by slag blended cements after exposure to high temperatures.