Optimisation of secondary waste gypsum for mechanical stability in road (base) and foundation

Abstract

This research was undertaken to close the knowledge gap in factory gypsum wastes. Tests were prepared on industrial by-products to determine suitability. Phase one tests revealed binary and ternary mixtures of gypsum wastes greater than 40% showed reduced strength at 7, 28 and 90 days. Mixture with the proportions of 15%V-B5G (Vitamin B5 Gypsum), 37.5%RAF (Reclaimed Asphalt Filler) and 47.5%GGBS attained the highest compressive strength of approximately 30MPa at 28 days. One of the dominant factors that influenced the strength of SYSTEM 2 and 2A was the presence of calcium sulphate-CaSO4 (CaO + SO3) in the PG / V-B5G materials, calcium silicate-CaSiO3 (CaO + SiO2) in the GGBS and the pozzolanic activity (SiO2 + Fe2O3 + Al2O3) in the RAF. The results suggest there are mixtures in all the SYSTEMS that are suitable for use as road (base) and foundation materials.