The Influence of the Different Cementitious Material on Self-Healing of Microcracks in Shotcrete

Abstract

Due to a particular construction process, the shotcrete structure is affected by external load, material aging, and external temperature during use, with cracks inevitably appearing. Cracks are formed from microstate gradually, and thus controlling the development of microcracks in the early phase can effectively improve the strength and impermeability of shotcrete. In this study, the method of laboratory experiment and analysis is adopted to study the effect of ettringite on achieving the self-healing effect of shotcrete. The test results show that: (1) after encountering water, ettringite effectively plays a microexpansion effect to fill the pores, helping shotcrete achieve the effect of waterproofing and self-healing, which is very suitable for single-layer lining structures with water seepage. (2) The content of ettringite is inversely proportional to the change law of pore structure. When the content of ettringite increases, the porosity and harmful pores proportion have a significant decrease. (3) Fly ash and mineral powder with a mixing amount of about 30% will not affect the strength of the concrete, while prolonging the time of the effect of ettringite, will effectively improve the impermeability of the shotcrete.