Optimized Alkaline-Activated Geopolymer Concrete with Recycled Aggregates: Mechanical and Microstructural Insights with Application
| International Journal of Civil Engineering |
| © 2025 by SSRG - IJCE Journal |
| Volume 12 Issue 6 |
| Year of Publication : 2025 |
| Authors : C B Supriya, B H Manjunath, Mamatha K H, Neeraj S.N |
10.14445/23488352/IJCE-V12I6P102
How to Cite?
C B Supriya, B H Manjunath, Mamatha K H, Neeraj S.N, "Optimized Alkaline-Activated Geopolymer Concrete with Recycled Aggregates: Mechanical and Microstructural Insights with Application," SSRG International Journal of Civil Engineering, vol. 12, no. 6, pp. 16-30, 2025. Crossref, https://doi.org/10.14445/23488352/IJCE-V12I6P102
Abstract:
Geopolymer concrete is increasingly being seen as a green alternative to OPC, with a significant reduction in greenhouse gas emissions and the use of industrial waste materials. This research explores the mechanical strength properties, durability, and microstructure of GPC using Class-F fly ash as a binder, M sand as fine aggregate, and recycled aggregate as coarse aggregate. An alkali-activated mix-design was formulated with sodium silicate and NaOH solution as activating agents to create an alkaline condition, where NaOH molarities were fixed at 10, 12 and 14 molar (M) and the stable liquid-to-binder ratio at 0.4, with alkaline liquid ratios being 2.5, 5, and 7.5. The specimens of GPC were dry-cured for 24 hours at 60°C at an elevated temperature in a hot air oven to promote polymerization and strength development. Experimental results showed that the mixture of 12M NaOH, an alkaline liquid ratio of 7.5, and an alkaline liquid-to-binder ratio of 0.4 showed the finest mechanical performance, with 52.74 MPa compressive strength, 4.68MPa flexural and 4.54MPa split tensile strength, with lower water absorption & disintegration under acid test. The GPC proved to be better concrete than OPC concrete when the test results were compared. Precast elements like paver block cast were for the optimized mix and tested. The microscopic view showed the compact and dense microstructure formed with reduced porosity by neatly developed geo-polymeric gels, which led to increased strength properties and durability.
Keywords:
Geopolymer concrete, Recycled aggregate, Alkaline activators, Microstructural analysis, SEM.
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