ANOVA-guided assessment of waste glass and limestone powder influence on ultra-high-performance concrete properties

Abstract

Ultra-high-performance concrete (UHPC) possesses remarkable structural and durability characteristics, yet its widespread acceptance is hindered by cost inefficiency and environmental concerns. To address these challenges, this study investigates the impact of waste glass and limestone powder as partial substitutes for silica fume and cement in UHPC. For this, three distinct formulations are studied (Control, Optimized-1, and Optimized-2), representing different dosages of waste glass and limestone powder. The research focuses on six critical properties (compressive strength, modulus of elasticity, ultrasonic pulse velocity, initial surface absorption, density absorption, voids, and chloride ion penetration) evaluated at different ages (1, 7, 28, and 90 days for compressive strength, and 7, 28, and 90 days for the remaining properties). So, a total of 171 test specimens were examined, with 3 samples for each age and formulation. Statistical analysis, using ANOVA, assessed and confirmed the significance of the factors in the experimental results. The findings provide comprehensive insights into the UHPC formulations, highlighting the influence of waste glass and limestone powder on specified properties over varying ages. The research reveals that, despite the optimized blends exhibiting lower compressive strength values, all mixes surpass the 150 MPa threshold for cylindrical samples at the 90-day mark. Moreover, the Control mix consistently outperforms the optimized blends in modulus of elasticity at all ages, meeting ACI 239 criteria. The void content analysis shows encouraging trends, with all formulations displaying voids of less than 5% on the seventh day, improving during the curing process. Notably, Optimized-2 demonstrates superior performance over the Control mix after 90 days. Chloride ion penetration is minimal for all blends after 90 days, confirming the effectiveness of mineral admixtures. ANOVA analysis confirms significant impacts of formulation and age on various UHPC characteristics, emphasizing the consistent reduction in performance with alternative mineral additions. The interaction between formulation and age implies variations in property evolution, suggesting potential convergence with alternative formulations.