Formulation and characterization of cleaner one-part novel fly ash/lime-based alkali-activated material

Abstract

With the advanced development in sustainable cementitious materials, cleaner one-part alkali-activated materials (AAM) have shown a significant effect on increasing compressive strength and reduction in CO2 emissions. This study is aimed to prepare one-part AAM based on fly ash (FA) and hydrated lime (LM) as main precursors. The impact of LM content as replacement of FA and activator dosage was evaluated on fresh and hardened properties of one-part FA/LM-based alkali-activated mortar. Fresh characteristics of AAM were evaluated through workability (setting time, flow table) and rheology, while hardened properties were evaluated by compressive strength, flexural strength, water absorption, durability test, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) tests. The test results revealed that the addition of FA/LM-based AAM increases the reactivity leading to earlier hardening of AAM. FA/LM-based AAM has shown higher compressive strength of 41.5 MPa. The rheology parameters show the increment in yield stress and plastic viscosity by increasing the lime content in the AAM. The activator dosage of sodium hydroxide increases the setting time and durability of AAM. The enhancement in strength and rheological parameters can be assigned to the enhanced geopolymerization reactions, leading to the formation of denser and compacted gels.