Eco-efficient self-compacting mortars incorporating dune sand and marble waste powders: Experimental optimization and life cycle assessment

This study investigates the combined rheological, mechanical, and environmental performance of self-compacting mortars (SCMs) incorporating dune sand powder (DSP) and marble waste powder (MWP) as sustainable clinker substitutes. A Box–Behnken design (BBD) coupled with life cycle assessment (LCA) was applied to optimize the water-to-binder ratio (0.35–0.45) and replacement levels (0–25%). Fresh (flow), hardened (compressive strength, CS), and durability (water absorption, W) properties were modeled alongside four LCA indicators: climate change (CC), energy resources (ER), material resources (MR), and human toxicity (HT). Moderate DSP and MWP substitutions in the 10–15% range led to notable performance improvements. The highest measured compressive strength reached 59.17 MPa in the optimized mixture, while water absorption decreased to approximately 4.5%, indicating a denser matrix. Environmental analysis via LCA showed reductions in CO₂ emissions by approximately 35% and energy consumption by nearly 20% relative to the control mix. These findings are supported by statistically robust quadratic models, with R² values exceeding 0.98 across all response variables. This integrated experimental–environmental framework confirms that DSP and MWP act as effective, low-cost supplementary materials capable of reconciling mechanical performance with sustainability goals. The findings provide a quantitative basis for designing eco-efficient SCMs adapted to regions rich in desert sand and marble waste.