Abstract

This study evaluates shrimp shell waste as a sustainable partial cement replacement in high-strength concrete (HSC). Two types of shrimp shell powders, uncalcined (USP) and calcined (CSP), were produced and characterized for their physical and chemical properties. Twelve concrete mixtures were developed using Central Composite Design (CCD) within a Response Surface Methodology (RSM) framework, incorporating USP and CSP at 5–20 % replacement levels, individually and in blends. Fresh (slump and density), mechanical (compressive, tensile, flexural strength, and modulus of elasticity), microstructural properties, and sustainability evaluation were examined. CSP mixtures outperformed USP, with the 15 % CSP mix achieving a 28-day compressive strength of 71.3 MPa and a modulus of elasticity of 44.7 GPa, attributed to matrix densification through carbonation. The 5 % USP and 10 % CSP blend exhibited the best overall performance. RSM analysis confirmed high model accuracy (R2 ≥ 0.98), and optimization using the desirability function identified this blend as the optimal mix (D = 1.000). Evaluation of sustainability showed that Hybrid mixtures 5 % USP +10 % CSP demonstrated about a 23 % reduction in cost/MPa with a reduction of 14.37 % CO2 and 11.6 % energy consumption compared to the control mix. The results demonstrate the viability of shrimp shell waste, particularly in calcined form, as an eco-efficient alternative for producing durable, high-performance concrete.