International Journal of Advanced Technology and Engineering Exploration ISSN (Print): 2394-5443    ISSN (Online): 2394-7454 Volume-12 Issue-128 July-2025
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Influence of accelerated curing on the mechanical and microstructural properties of fly ash–GGBS-based geopolymer concrete with partial recycled aggregate replacement

Pooja S M1 and S V Venkatesh2

Research Scholar, Civil Engineering,PES University, Bengaluru, Karnataka,India - 5600851
Professor, Civil Engineering,PES University, Bengaluru, Karnataka,India - 5600852
Corresponding Author : Pooja S M

Recieved : 31-July-2024; Revised : 12-July-2025; Accepted : 27-July-2025

Abstract

Geopolymer concrete (GPC), an eco-friendly alternative to traditional Portland cement concrete, is produced using industrial by-products such as fly ash and ground granulated blast furnace slag (GGBS). Both fly ash and GGBS by-products of coal combustion are rich in silicon dioxide (SiO2), aluminium oxide, and iron oxide, which contribute to enhanced long-term strength and durability. The inclusion of these materials promotes the formation of calcium silicate hydrate (C–S–H) gel, complementing the geopolymeric gel and improving the concrete’s overall performance. In this study, GPC was produced using a 70:30 blend of fly ash and GGBS and partially replaced with recycled concrete aggregates (RCA) in a 70:30 ratio with natural aggregates. An alkali activator solution was used, comprising sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) in a 1:2.5 ratio, with a NaOH molarity of 12M and an alkaline activator-to-binder ratio (AA/B) of 0.45. Curing conditions included oven curing, accelerated curing (using boiling water), and open-air curing, and the results were compared with conventional cement concrete. Accelerated curing enabled the GPC to attain up to 50% of its compressive strength within the first 24 hours, comparable to oven curing and approximately 50% higher than that of cement concrete. In contrast, open-air curing resulted in only 2 MPa strength gain in the same duration. Furthermore, the flexural and split tensile strengths were significantly higher in GPC subjected to accelerated curing. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis confirmed enhanced geopolymerization due to the thermal energy supplied by the boiling water during accelerated curing. This enhanced geopolymerization contributed to notable improvements in compressive, tensile, and flexural strength, suggesting potential for superior long-term performance.

Keywords

Geopolymer concrete, Fly ash, Ground granulated blast furnace slag (GGBS), Recycled concrete aggregate (RCA), Alkali activation, Accelerated curing, Mechanical properties enhancement.

Cite this article

SM Pooja, Venkatesh SV. Influence of accelerated curing on the mechanical and microstructural properties of fly ash–GGBS-based geopolymer concrete with partial recycled aggregate replacement. International Journal of Advanced Technology and Engineering Exploration. 2025;12(128):1021-1034. DOI : 10.19101/IJATEE.2024.111101381

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