Performance Assessment of Sustainable Self-Compacting Concrete Incorporating GBFS, CPA, and CSA as Cement Replacement Materials

Self-Compacting Concrete (SCC) has become an important advancement in concrete technology due to its ability to flow under its own weight, fill formwork completely, and pass through congested reinforcement without external vibration. These characteristics improve construction efficiency, reduce labor and noise, and enhance surface finish and structural reliability (Okamura & Ouchi, 2003; EFNARC, 2005). As a result, SCC is increasingly used in complex structural applications. However, the production of SCC often requires high cement content and carefully controlled aggregate grading, which can increase cost and environmental impact. In recent years, growing concerns over climate change and resource depletion have driven research toward more sustainable concrete materials. One widely adopted approach is the use of supplementary cementitious materials (SCMs) to partially replace ordinary Portland cement. Ground Granulated Blast Furnace Slag (GBFS), a by-product of the steel industry, has been extensively studied due to its ability to reduce carbon emissions while improving long-term mechanical performance and durability of concrete (Shi et al., 2015; Thomas, 2018). Studies conducted between 2020 and 2025 have confirmed that GBFS can enhance later-age compressive strength in SCC by refining pore structure and contributing to continued hydration, although early-age strength may be slightly reduced depending on replacement level (Singh et al., 2021; Li & Huang, 2023). In addition to cement replacement, the selection and proportioning of aggregates play a critical role in determining SCC performance. Aggregate characteristics such as shape, surface texture, and grading strongly influence fresh properties, particularly flowability, passing ability, and segregation resistance (Neville, 2011). Recent research has shown that the use of alternative or processed aggregates, including Crushed Stone Aggregate (CSA) and Coarse Processed Aggregate (CPA), can significantly affect SCC rheology and strength development. Angular and rough-textured aggregates tend to increase internal friction, thereby reducing workability unless compensated by mix design adjustments or chemical admixtures (Mohammadhosseini et al., 2021; Wang et al., 2022). Workability has consistently been identified as one of the most sensitive properties of SCC incorporating sustainable materials. Several studies conducted in the last five years report that increasing the proportion of SCMs or alternative aggregates can reduce slump flow and stability if not properly optimized (Abbas et al., 2023; Safiuddin et al., 2021). Conversely, appropriate use of GBFS has been shown to improve the viscosity and cohesiveness of SCC, contributing to stable flow behavior when combined with suitable aggregate grading (Zhang et al., 2022).