Performance Evaluation of Sustainable High-Performance Concrete Incorporating Supplementary Cementitious Materials in Pozzolanic Cement Systems

The growing demand for sustainable high-performance concrete (HPC) requires reducing clinker content while maintaining durability under aggressive environments. However, the combined effects of supplementary cementitious materials (SCMs) on mechanical performance, transport properties, sulphate resistance, and thermal stability remain insufficiently adopted, especially in blended cement systems. This study addresses this gap by evaluating the performance of SCM-based HPC produced with Portland cement (CEM I) and pozzolanic cement (CEM IV) under transport conditions, elevated temperature, and sulphate exposure using a unified performance-based approach. Fly ash (FA), and ground granulated blast-furnace slag (GGBS), silica fume (SF), and calcined bentonite (CB) were used as partial replacement of the two cement types. Results show that compressive strength reached up to 61 MPa at 28 days and increased further up to 180 days (12.5–28.8%), with CEM IV outperforming CEM I, particularly in GGBS- and FA-based systems. At 28 days, splitting tensile and flexural strengths of GGBS-based systems improved by up to 46% and 41%, respectively. Transport properties improved in CEM IV mixes, particularly with GGBS (60–70% lower permeability), while CB adversely affects durability at higher replacements. Under elevated temperatures, GGBS-based mixes retain the highest residual strength (65–70% at 800 °C), whereas CB-based mixes show the lowest resistance. Moderate SCM replacement (10–20%) enhances sulphate resistance (90–106% strength retention), while higher levels (30%) reduce performance. Sustainability analysis confirms that CEM IV mixes reduce CO2 emissions and energy, with the CO2/strength ratio as a reliable indicator. A key contribution of this study is the integrated comparison of CEM I and CEM IV systems, highlighting how SCMs reactivity and cement type influence performance. Overall, this study demonstrates that optimal performance requires balancing clinker reduction with SCM selection within an integrated durability–sustainability framework.