Freeze–thaw performance of self-compacting concrete with GGBFS, fly ash and limestone powder: linking strength loss to air-void parameters

Abstract

Abstract Comparative evidence on how different supplementary cementitious materials affect freeze–thaw performance and air-void system characteristics of self-compacting concrete (SCC) under consistent mixture conditions remains limited. This study provides a direct comparative assessment of ground granulated blast-furnace slag (GGBFS), fly ash (FA), and limestone powder (LM) as partial cement replacements in SCC within a unified mix-design framework. SCC mixtures incorporating 15% and 30% of GGBFS, FA, or LM were evaluated for fresh properties (slump flow, V-funnel, L-box) and for mechanical performance (compressive and splitting tensile strength, modulus of elasticity) at 28, 56, and 90 days. Freeze–thaw performance was evaluated after 150 cycles, while the hardened air-void system was characterized using total air content (A), micro-air content (A 300 ), and spacing factor (L). Selected mixtures were examined by SEM/EDS and complemented by a limited quantitative SEM texture assessment at fixed magnification to support microstructural interpretation. Statistical analysis (two-way ANOVA and Tukey HSD) and regression-based relationships were used to strengthen the comparison. The results show that FA primarily improved flowability, reaching a slump flow of 740 mm at 30% replacement, whereas GGBFS provided the most favorable balance between late-age mechanical performance and freeze–thaw resistance, achieving 69 MPa compressive strength at 90 days and only 0.2% mass loss and 1.0% strength loss after F150 at 30% replacement. LM contributed to stabilizing the protective air-void network, while the lowest spacing factor (L = 0.11 mm) was observed for GGBFS30 and LM30. Importantly, freeze–thaw strength loss was more strongly associated with spacing factor L than with total air content, highlighting void spacing as a practical durability-oriented predictor for SCC incorporating SCMs. Overall, the findings support clinker reduction strategies while maintaining durable SCC performance.