Influence of Local Aggregate Type and Morphology on the Rheological and Mechanical Properties of Self-Compacting Concrete in Tropical Conditions

Abstract

This study experimentally investigates the influence of locally sourced aggregates from southern Benin on the fresh and hardened properties of self-compacting concrete (SCC). A comparative experimental program was conducted using three sand types (river, lagoon, and crushed) and two gravel types (natural and crushed), resulting in 18 concrete mixtures classified as ordinary vibrated concrete (OVC), S4-class concrete (S4C), and SCC. Fresh-state performance was evaluated using standardized tests (slump-flow, J-ring, V-funnel, and L-box) in accordance with EN and EFNARC guidelines, while compressive and flexural strengths were measured at 14, 28, and 90 days. Results indicate that SCC mixtures incorporating natural aggregates exhibited improved flowability and satisfactory passing ability, with slump-flow diameters ranging from 670 to 780 mm and L-box ratios exceeding 0.80. In contrast, crushed aggregates enhanced mechanical performance, increasing 28-day compressive strength by up to 15%, with maximum values reaching 52 MPa. However, the combined use of crushed sand and crushed gravel significantly reduced passing ability, as evidenced by lower L-box ratios and increased V-funnel flow times. Overall, most SCC formulations satisfied EFNARC performance criteria, demonstrating the feasibility of producing structurally reliable SCC using indigenous tropical aggregates when appropriate mix proportioning and admixture dosage are applied. The findings confirm a trade-off between fresh-state deformability and hardened-state strength governed by aggregate type and grading balance, and provide experimentally validated guidance for optimizing SCC mix design in Sub-Saharan construction contexts.