Thermal processing of ca-bentonite ore by calcination method to use in geopolymer concrete with additive materials

In this study, a calcined calcium bentonite clay was used as a partial substitute with fly ash as fine aggregate in the production of geopolymer concrete (GPC). Besides, to recycle the tailings from metallurgic factories, ferrochrome slag was used as coarse aggregate and fly ash was used to production of lightweight geopolymer concrete with expanded polystyrene (EPS) with a size of 3mm, 5mm, and 7mm. NaOH and Na2SiO3 were used as basic activators. The NaOH concentration was fixed at 14 M and the Na2SiO3 concentration was fixed at 5 M. Uniaxial compressive strength (UCS), point load strength (PL), sonic speed (PSS), and shore hardness (SH) were measured on experimental samples to evaluate the ratios that to obtain the best results. The experiments were carried out by mixing 5% calcined calcium bentonite (CCB), 5% ferrochrome slag (SG), and fly ash (FA). The average properties of GPC tested after 28 days are as follow; bulk density was obtained at 1792 kg/m3, with a uniaxial strength of 51.33 MP, a point load resistance of 14.05 KN, and a speed of sound of 6.41 km/s, and a shore hardness of 63.17 mm. The bulk density of lightweight concrete with EPS was (1592 - 1264) kg/m3.