Studies on high performance alkali activated slag concrete mixes subjected to aggressive environments and sustained elevated temperatures

Abstract

In contemporary constructions, there is a continuous drive for enhancing the performances of concrete mixes, both green and as well as on hardened state. Again there are simultaneous efforts to take full advantage of all the various fast-track, state-of-art construction technologies, leading to early completion of efficient, economical and eco-friendly infrastructure projects. The present authors have developed a new class of high performance self-compacting, alkali activated slag concrete mixes (HPAASC) using three industrial by-products, all obtained from iron and steel industry and have evaluated them for their strength properties. While these HPAASC mixes have higher compressive strengths (about 70–90 MPa) and reasonable split-tensile and flexural strengths, they are also self-compacting in nature. In the present paper, the durability performance of this class of mixes on long-term exposure to aggressive environments like acids, sulphates and chlorides is discussed. Strength deteriorations of the standard test specimens subjected to 5% concentrated sulphuric acid solution and so also in 10% magnesium sulphate solution were monitored for a period of one year. The impermeability of the mixes against chloride-ions was evaluated using both Bulk diffusion test (BDT) and the Rapid chloride penetration test (RCPT). Further these mixes were also evaluated for their performance on exposure to sustained elevated temperatures in the range of 200–800 °C. All the specimens were further analysed for their microstructural studies. Results in the present study indicate that, all the HPAASC mixes exhibit better resistances to aggressive environments and sustained elevated temperatures as compared to the OPC-based reference concrete mix.