Influence of Ambient and Oven Curing on Strength Development of Fly Ash–Based Geopolymer Concrete and OPC Concrete

Abstract

The cement industry remains one of the largest contributors to global CO₂ emissions, underscoring an urgent demand for sustainable alternatives in construction materials. Geopolymer concrete has emerged as a promising eco-friendly replacement for ordinary Portland cement (OPC), owing to its capacity to utilize industrial by-products such as fly ash and its potential to substantially reduce carbon emissions. Among various supplementary materials, Class F fly ash presents a viable pathway for sustainable development through complete cement substitution. Although extensive research has investigated the mechanical performance of geopolymer concrete, the underlying strength development mechanisms remain critical for determining its suitability across diverse construction applications. Existing studies indicate notable sensitivities related to compressive strength development and curing conditions, which must be addressed to enable wider adoption in structural practice. In present study, M25, M30, and M40 grade geopolymer concrete mixes were produced using 100% Class F fly ash as a binder. Sodium hydroxide and sodium silicate solutions were employed as alkaline activators at a concentration of 13M in the fresh mix. The experimental programme was designed to assess compressive strength at different curing ages under two curing regimes—oven curing and ambient curing—with focus on structural reliability and sustainability. The findings are expected to highlight the potential of geopolymer concrete as a durable and environmentally responsible construction material.