Environmental sustainability and cost-benefit analysis of concrete containing date palm ash and eggshell powder: A response surface methodology approach

The cement industry contributes about 7–8 % of the global CO2 emissions. Therefore, to reduce the embodied CO2 emission from cement, its usage in concrete needs to be reduced. Agricultural waste from date palm trees is one of the major waste materials in middle east countries like Saudi Arabia. In this study, the date palm waste was processed to date palm ash (DPA) and used as supplementary cementitious material (SCM) in concrete to reduce the embodied CO2 emissions. Due to the weak pozzolanic reaction of the DPA, it was blended with eggshell powder (ESP) owing to its high calcium oxide content. Cement was replaced with DPA at 0 %, 10 %, 20 %, 30 % and 40 % by weight. ESP was added in proportions of 0 %, 1 %, 2 %, 3 % and 4 % by mass of binder. Response surface methodology (RSM) was used to carryout experimental design and sustainability analysis. The findings showed that using either DPA as SCM or blends of DPA and ESP as binder materials significantly reduced embodied CO2 emissions and cost, enhanced eco-strength efficiency of the concrete. The mathematical models developed for predicting the embodied CO2 and cost of the concrete were higher significant with very good accuracy. From the optimization results, an eco-sustainable concrete in terms of lower cost and embodied CO2 was achieved by blending 21.3 % DPA as SCM and 2.3 % ESP by mass of binder in the concrete.