The self-healing properties and mechanism of the cracked fly ash-based engineered geopolymer composites (FA-EGC): effects of water and temperature

AbstractIn this article, the self-healing properties and mechanism of cracked fly ash-based Engineered Geopolymer Composites (FA-EGC) in different environments are studied. Four kinds of environments (air, wet-dry cycles, 20 °C water, and 40 °C water) are chosen to simulate real service environments. The tensile property, ultrasonic pulse velocity, crack characteristic, and water absorption of FA-EGC are measured to evaluate the self-healing properties. The test results show that the existence of water and the increasing of temperature can benefit the self-healing performance of FA-EGC. In addition, the 28-day self-healing products are determined by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) to explore the mechanism of the self-healing in different environments. The results demonstrate that N–A–S–H gels could be the main self-healing products in the air condition. While in the other environments with water, the (N/C)–A–S–H gels would be the primary products.Keywords: fly ashengineered geopolymer compositesself-healingmechanismwatertemperature AcknowledgementsThe authors acknowledge the financial supports received from the National Natural Science Foundation of China [No. 52178241 and 52242807], the National Key Research and Development Program of China [No. 2021YFB3802001 and 2019YFE0112600], the Fundamental Research Funds for the Central Universities [No. 22120220599].Disclosure statementThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article.