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Self-healing in metakaolin-based geopolymers with crystalline admixture, expansive agent, and hydrated lime

2024; Elsevier BV; Volume: 418; Linguagem: Inglês

10.1016/j.conbuildmat.2024.135391

1879-0526

Allan Guimarães Borçato, Ronaldo A. Medeiros-Junior,

Building materials and conservation

This study investigated the self-healing of metakaolin-based geopolymers by incorporation of crystalline admixture (CA), expansive agent (EA), and hydrated lime (HL). Cracks were made in the samples at 3 days of age and their sealing was checked during 112 days of water immersion. The phases formed during self-healing were evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses. The results showed that self-healing did not occur in the mixtures without HL incorporation due to the insignificant calcium content in the material. However, partial self-healing occurred in the 10% HL mixtures. Therefore, the calcium from HL was predominant for the occurrence of self-healing in geopolymers. SEM/EDS analysis showed that calcite formation was the main phase of self-healing. However, C-A-S-H gel and vaterite were also identified as self-healing products. In summary, the results showed that EA is not suitable and CA has the potential to improve self-healing in geopolymers.