Physio-mechanical performance of super absorbent polymer modified low calcium fly ash-based geopolymer concrete against various curing regimes

Abstract

This research investigates the effect of internal curing (IC) with super absorbent polymer (SAP) on low calcium fly ash-based geopolymer concrete (GPC) with water, ambient and heat curing regimes. The impact of SAP on workability, shrinkages, physical, mechanical and microstructural properties of GPC are studied with three mixes (R0.5, R0.554, and S0.554). The liquid absorption of SAP was greater in water than the simulated alkaline solution of GPC. The SAP-modified mixture S0.554 has 0.3% SAP by weight of fly ash, and its effective alkali activator to fly ash ratio (AA/FA) is similar to mix R0.5, while its total AA/FA ratio is similar to mix R0.554. The results showed that inclusion SAP reduced shrinkage in GPC with comparable compressive strength and decreased workability. Additionally, at an equivalent effective AA/FA ratio, SAP increased compressive strength up to 7%. The flexural and tensile strength were enhanced along with physical properties by incorporating SAP as it densified the microstructure, which was proved by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The performance of SAP was better when GPCs were ambient cured compared to water and heat curing