Kabange B. Numbi, Martin T. Mpinda, Sissou Zakari, Kisimba T. Ngobola, Ngoie D. Songe
Abstract: The cement industry consumes huge amounts of energy and emits CO2, the main greenhouse gas. With the promotion of sustainable development, particular attention is drawn to how ecological materials with similar or better properties should be developed than ordinary Portland cement, and geopolymer cement has been recognized as one of the most promising materials. This study investigated the effect of SiO2/Al2O3 ratio and curing time on the mechanical and chemical properties of synthetized geopolymers (SCAA) from activated clay (AA), copper slag (SC) and Na2SiO3-NaOH. Five (5) slag geopolymers (SCAA) were synthetized using two different proportions of clay and copper slag: CSAA1 (5 % AA-95 % CS), CSAA2 (10 % AA-90 % CS), CSAA3 (15 % AA-85 % CS), CSAA4 (20 % AA-80 % CS), and CSAA5 (25 % AA-75 % CS). The best stability properties were observed for the SCAA5 with SiO2/Al2O3 ratio of 2.23 and an acidity index of 1.3. This research has a large environmental impact as it helps to valorise copper slags and immobilize their containing ETMs, therefore it also indirectly aids to reduce the energy use and direct CO2 emissions during the manufacture of ordinary Portland cement.
Keywords: geopolymer, greenhouse gas, ordinary Portland cement, stability, acidity index