High-volume limestone powder concrete as a low-carbon material for reinforced concrete beams: Experimental evidences and code predictions of long-term behaviour

Driven by the growing demand for more sustainable concrete production and the limited availability of reactive cementitious materials, limestone powder has emerged as an environmentally and economically viable alternative for partial replacement of ordinary Portland cement (OPC). Although numerous studies in the past decade have investigated the physical and mechanical properties of high-volume limestone powder concrete (HVLPC), their short- and long-term structural performance remains unexplored. Despite being an essential input parameter for structural analysis, material properties are insufficient for reliable conclusions. To address this gap and contribute to a better understanding of the material’s behavior, six simply supported reinforced concrete beams were designed (2 OPC and 4 HVLPC with a 45 % cement reduction) and tested under sustained loading for 1000 days. The experimental program included continuous monitoring of deflections, strains in concrete and reinforcement, crack width development, shrinkage, and creep. Results showed that HVLPC achieved mechanical properties comparable to OPC, but delivered notably improved structural performance. Over 1000 days, HVLPC beams exhibited 18–25 % lower long-term deflections, 21–32 % narrower cracks, as well as reduced shrinkage (14–22 %) and creep (17–24 %). Further analyses showed that the Eurocode 2 (EN 1992–1–1:2023) prediction model consistently underestimated shrinkage and creep, which was effectively corrected through model calibration, resulting in very good agreement with experimental observations. Finally, analytical predictions of long-term deflections, using experimental material properties as input, correlated well with measured values, showing an average deviation of about 10 %.