Development of GGBS Waste-Based Modified Self-Healing Concrete Incorporated with Bentonite

Purpose: This research focused on the development of self-healing concrete using GGBS (Ground Granulated Blast Furnace Slag) and Bentonite as partial replacements for cement.  Design/Methodology/Approach: Fresh concrete was examined using slump tests, while hardened concrete properties were evaluated using compressive and split tensile strength tests and density tests. One hundred forty-four (144) hardened samples were cured in water for strength tests, while the air and water curing methods were used to study the self-healing properties of ten (10) samples. The curing days considered ranged from 7 to 90 days. The microstructural properties of the hardened samples were examined using a Scanning Electron Microscope and Electron Dispersive X-Ray (SEM-EDX) analysis. Findings: The slump tests showed that GGBS and Bentonite absorb water at higher rates than cement. The test on the hardened concrete samples also showed that the modified samples exhibited higher mechanical properties than the control samples. Overall, the optimum GGBS and Bentonite composition that exhibited the best mechanical performance is mix G2B4, which utilised 2% GGBS and 4% Bentonite. Compared with the control experiment, G2B4 exhibited compressive strength higher than the control, with a 13% difference at 56 days of curing, demonstrating self-healing under water-curing conditions. Research Limitation: The study was limited to specific replacement levels of ground granulated blast furnace slag and bentonite, as well as controlled laboratory conditions; hence, the self-healing performance may vary under different environmental exposures and crack widths. Practical Implication: The findings indicate that the combined use of GGBS and bentonite, within the replacement levels, may not significantly enhance autonomous crack healing, suggesting the need for supplementary healing agents or modified mix designs in practical applications. Social Implication: Improving understanding of self-healing limitations in concrete contributes to more reliable, durable infrastructure, ultimately supporting public safety and reducing long-term maintenance costs for society. Originality / Value: This study demonstrates the feasibility of producing self-healing concrete using GGBS and Bentonite in a single mix to mitigate carbon dioxide emissions and the adverse effects of sand mining. The study also established a 2% GGBS and 4% Bentonite mix as the optimum.