Potential Application of Heat Cured Eggshell Powder and Flyash-Based Geopolymer in Pavement Construction

Abstract

In this research, the application of eggshell powder (ESP) and flyash (FA) as calcium oxide and alumino-siliceous precursors to produce a feasible geopolymer for pavement construction was studied. Effect of heat curing on long-term mechanical strength development of the geopolymer was also evaluated. The ESP is a waste-by-product produced from crushing waste eggshells, whilst FA is a waste-by-product generated from the coal-fired electricity production plant. Geopolymer composites were produced using three activator ratios Na2SiO3/NaOH − 0.5, 1.0, and 2.0 with a fixed 10 M concentration of NaOH. The curing process was done at 50 °C and 80 °C temperatures for 7 days, 28 days, and 56 days. The optimum activator content (OAC) providing the maximum dry unit weight (MDU) was found to increase with an increment in activator ratio and FA replacement ratio. Na2SiO3/NaOH − 2.0 was found as an optimum activator ratio providing the highest unconfined compressive strength (UCS) and the highest split tensile strength (STS). Similarly, optimum precursor ratio providing the highest UCS followed by highest STS was found as ESP50:FA50. Microstructural analysis showed that cementitious products were formed for the ESP-FA geopolymer at the optimum activator ratio and heat conditions.