Effect of calcium carbide residue and superplasticizer dosages on the mechanical and microstructural properties of fly ash based geopolymer composites
Gaddam Kalpana, Chappidi Hanumantha Rao, Musa Adamu, Ashwin Raut, Yasser E. Ibrahim
Abstract
ABSTRACT The role of calcium-rich waste like Calcium carbide residue (CCR) in enhancing the performance of geopolymer remains inadequately explored. This study investigates the structural, mechanical, and microstructural behaviour of low-calcium fly ash (FA)-based geopolymer composites modified with varying CCR contents (0%, 10%, 20%), sodium hydroxide molarities (8M, 10M, 12M), and superplasticizer dosages (0%, 1%, 2%). Results revealed that 10% CCR combined with 2% superplasticizer and 12M NaOH offered optimal performance, achieving a 16.8% increase in compressive strength, a 144.8% rise in tensile strength (3.06 MPa), and a 145.5% improvement in flexural strength (3.83 MPa). Flowability improved by 15% with higher superplasticizer dosage, whereas excessive CCR (20%) adversely affected strength and porosity. Microstructural observations confirmed the synergistic formation of N-A-S-H and C-S-H gels in optimized mixes. These findings highlight CCR’s viability as a sustainable calcium source in geopolymer technology, promoting enhanced mechanical performance and environmental sustainability through industrial waste valorisation.