The potential of binary blended geopolymer binder containing Ijero-Ekiti calcined kaolin clay and ground waste window glass

The aim of this study was to investigate alkaline reactivity potentials of calcined clay and ground waste window glass with NaOH/Na2SiO3 solution to form geopolymer, an inorganic binder. A calcined clay (CC) sourced from Ijero-Ekiti, Nigeria, was replaced by various proportions (0, 25, 50 and 75%) of ground waste window glass (GWWG) and subjected to alkaline activation by NaOH/Na2SiO3 solution. X-ray florescence (XRF) and Fourier Transform Infrared (FTIR) spectroscopy were applied to characterise the materials and the resulting geopolymers. The XRF results revealed the main oxides of Ijero-Ekiti clay as SiO2 and Al2O3 and for GWWG as SiO2 and Na2O. The FTIR results confirm the clay as kaolin clay which is suitable for geopolymer synthesis. The synthesised geopolymer binders were cured at room temperature for 7, 14, 21 and 28 days. Their compressive strengths, dry density and water absorption were measured. Geopolymers with ground waste window glass (GWWG) indicated higher strengths at both early and late curing times. The final 28-day compressive strength values of GWWG-CC-based geopolymers observed was in the range of 17.3±0.6 to 23.1±0.7 MPa compared with 11.6±0.4 to 14.5±1.4 MPa for 100% CC-geopolymers. Calcined clay replacement up to 75% glass yielded the highest strength. Addition of window waste glass enhanced both early and late strength gain of the geopolymers and improved physical properties. Therefore, GWWG-CC-geopolymers could serve as potential binders in making green construction and building materials.   Key words: Ijero-Ekiti kaolin clay, waste window glass, recycling, clay-waste-glass-geopolymer, compressive strength development.