Influence of copper slag on Mechanical, durability and microstructural properties of GGBS and RHA blended strain hardening geopolymer composites

Abstract

To enhance sustainability, two major slag based industrial wastes viz., Ground Granulated Blast furnace Slag (GGBS) and copper slag were adopted in this study to develop Engineered Geopolymer Composites (EGC) replacing commonly used fly ash and silica sand. A small fraction of agricultural waste viz., Rice Husk Ash (RHA) was also used as a part of the binder which proved to improve the efficiency of GGBS in geopolymer composites. Higher volume of industrial wastes were intended to reduce the impacts of CO2 and land degradation due to cement production and dumping of industrial wastes respectively. PolyVinyl Alcohol (PVA) fibres and sodium-based activators were considered from the literatures to impart the strain-hardening and geo-polymerization reaction respectively. Dosages of activator, superplasticizer and extra water contents were optimized based on the workability test. Keeping the other mix-design factors as constant, the effect of the content of copper slag in proportion with Manufactured Sand (M Sand) in the proposed EGC mixtures were studied in this research with respect to mechanical, durability and microstructural parameters. Content of copper slag anything above 60% resulted in poor bonding and segregation. Replacement of copper slag upto 40% produced the maximum compressive strength of 39.6 MPa after 90 days of ambient curing conditions. The best among the mixes was M60C40 (40% copper slag) which recorded about 1.98 MPa and 12.75 MPa of tensile and flexural strength respectively with a maximum tensile strain capacity of about 6.12%. The specimens were excellent in resisting the seawater attack which did not show any significant weight or strength loss whereas sulphate attack showed considerable strength loss upto 5%. During the microstructural investigations with Scanning electron microscope (SEM) and Energy Dispersive X-ray analysis (EDAX), the effects caused by the aggressive environments could be clearly visualized with the observations towards the internal physical structure and intensity of chemical elements respectively.