Influence of bagasse ash powder and marble powder on strength and microstructure characteristics of alkali activated slag concrete cured at room temperature for rigid pavement application

In this research, an attempt is made to partially replace ground granulated blast furnace Slag (GGBS) with a binder rich in SiO₂ and CaO in alkali activated slag concrete (AASC) to increase workability and setting time. GGBS is replaced with bagasse ash powder (BAP) in 5%, 10%, and 15% of the binary mix, and subsequently with marble powder (MP) in 5% and 10% of the binary mix. After establishing the best mix for both binder replacements, a ternary mix with 5% BAP and 10% MP is created. The fine aggregates used in the comparison are 100 % river sand and slag sand. 10 M sodium hydroxide and the alkaline to binder ratio is 0.4, were used. Mechanical properties such as compressive strength, split tensile strength, and flexural strength are performed cured at 1, 3, 7, and 28 days samples. To further understand the intrinsic mechanism of strength development, microstructure, morphology and mineralogy on AASC are investigated. Based on the findings, it can be inferred that AASC mixes have a higher strength than OPC mixes. The mechanical strengths of the AASC binary mix with 10% MP and 5% BAP are higher. The microstructural analysis reveals the mixes developed with BAP and 100 % GGBS, had a denser microstructure than the normal mixes. The mechanical properties obtained for most of the AASC mixes are significantly higher than the IRC SP:62-2014 recommendations for rigid pavements for low volume roads.