Mechanical, microstructural characteristics and sustainability analysis of concrete incorporating date palm ash and eggshell powder as ternary blends cementitious materials

Cement production causes a threat to environmental sustainability owing to the enormous volume of greenhouse gas releases and high energy consumption. Similarly, agro-industrial waste contributed significantly to envi-ronmental pollution when disposed of in landfills. Waste from date palms is one of the main agro-waste generated in Saudi Arabia. This waste is normally disposed of without treatment or burnt for energy. The date palm ash (DPA) due to its pozzolanic properties could be suitable for use as supplementary cementitious material (SCM) in concrete. However, due to its weak or slower pozzolanic reactivity, the DPA negatively affects the performance of concrete. In this research, the DPA was used as a SCM in concrete. Eggshell powder (ESP) owing to its abundant calcium oxide content was used as an additive to the concrete containing other pozzolanic materials with high silica content. Cement was partially replaced with DPA at dosages between 10% to 40%, and ESP was added at different proportions between 1% to 4% by weight of the binder. The workability of the concrete was decreased with adding blends of DPA and ESP. The mechanical strengths (compressive, flexural, and tensile strengths), modulus of elasticity (MoE), water absorption, and porosity of the concrete were nega-tively affected by adding DPA. Blending up to 30% DPA with up to 3% ESP as cementitious materials help alleviate the adverse effects of the DPA on the strengths, MoE, and durability performance of the concrete. DPA increases pore volume and porosity by decelerating C-S-H production through its slower pozzolanic reaction at early ages. DPA reduced total embodied CO2 emissions and enhanced the eco-strength efficiency of the concrete. Using DPA and ESP blends in concrete improves performance, minimizes environmental effects, and reduces CO2 emissions during cement production.