Thermal strength of the alkali-activated slag concrete

Every structure may experience elevated temperatures during its service life. Heat changes the physical and mechanical properties of concrete. The increasing need for cement for concrete preparation has had an environmental impact including about 7 percent share of CO2 emissions to the atmosphere. Thus, it is essential to provide alternative products to move on the path of sustainable development to reduce these effects. One of the strategies for environmentally friendly concrete production is to use alkali activated slag concrete (AASC). Alkali-activated slag (AAS), if designed properly, could be considered as a proper replacement for Portland cement. In this study, alkali-activated slag concrete specimens with different slag contents were placed in a furnace at different temperatures up to 800 ˚C. The effect of temperature on the mass loss and the compressive strength of the AAS concrete was investigated. Portland cement specimens were also prepared to be compared with the AAS concrete ones. The data was analyzed using the T-test method, as well as one-way and two-way ANOVA. Scanning electron microscopy images were used to compare the microstructures of the AAS concrete and the normal concrete at different temperatures. Also, the change in the structure of the pores of the AAS concrete was investigated by employing mercury intrusion porosimetry. Overall, the results showed the very good thermal performance of the AAS concrete in comparison with that of the Portland cement one.