Empirical relations between material characteristics and performance of sawdust ash-admixed conplast concrete

Abstract Concrete production’s environmental impact has driven the use of supplementary cementitious materials like sawdust ash (SDA) and admixtures such as Conplast to enhance sustainability and performance. This study develops empirical relations for SDA-admixed Conplast concrete, investigating material characteristics, fresh and hardened properties, and their interactions at SDA replacement levels of 0–40%. Materials were characterized, including cement (CaO: 63.7%, SiO₂: 19.9%), SDA (SiO₂: 63.4%, specific gravity: 2.29), and Conplast (specific gravity: 1.18). Fresh properties (consistency, setting times, slump) and hardened properties (water absorption, density, compressive strength) were tested per ASTM standards. Statistical analysis included Pearson correlations, linear/quadratic regressions, and ANOVA. Two-way ANOVA assessed SDA and age effects with Tukey post-hoc for significant factors. Results showed SDA reduced slump (linear: y = −0.7x + 129, R² = 0.98) and setting times but optimized strength at 10% SDA (24.7 N/mm²). Inter-property relations revealed moderate correlations (e.g., slump vs. density, r = −0.57) and strong quadratic fits (e.g., initial setting vs. density, R² = 0.93). Oxide analysis highlighted SiO₂’s role (quadratic R² = 0.97, p = 0.03). Hardened relations confirmed porosity-density links (R² = 0.91). SDA-Conplast synergy improves durability at 10–20% replacement, reducing emissions while maintaining performance. Findings guide sustainable mix design, with recommendations for 10% SDA for balanced properties. These regressions are exploratory and indicate correlation rather than causation or predictive capability due to the limited number of replacement levels (five data points).