Study On Self-healing Properties Of Cement-based Materials Based On Encapsulated Shale Pottery Sand

The development of self-healing concrete can effectively improve the durability of concrete structures and prolong the service life of structures,and the research on selfhealing properties of cement-based materials is the foundation of the development of selfhealing concrete.At present,the technology of microcapsules within healing agents is one of the more effective self-healing methods.However,the compatibility problem between wall materials and cement matrix has a great impact on the healing effect.Therefore,scholars at home and abroad have begun to explore the method of inorganic porous materials within healing agents.This method can not only solve the compatibility problem,but also enrich the research angle and use scope of self-healing technology,and then promote the development of concrete structures in the direction of intelligence and green.To this end,this article used inorganic porous materials as the carrier of healing agents,and studied its effect on the self-healing properties of cement-based materials.This article mainly includes the following research contents and achievements:(1)The shale pottery sand was used as the carrier of sodium silicate healing agent,and the encapsulated shale pottery sand with excellent performance of absorption and retention was prepared.Firstly,through the observation of cross-sectional morphology and determination of absorption rate,shale pottery sand was selected as the carrier of healing agent.Then,the effect of vacuum method on absorption and retention capacity was analyzed,and the optimal level combination and maximum adsorption during adsorption process were obtained by orthogonal test with four factors and three levels.Finally,the shale pottery sand was encapsulated and the effect of encapsulation was evaluated by mass loss method and ion dissolution method.(2)The changes of fracture transmission performance and crack width under different healing environments were analyzed,and the healing effect of encapsulated shale pottery sand in cement-based materials was explored.Firstly,the three healing environments of standard curing room,deionized water and saturated calcium hydroxide solution were determined.Secondly,the capillary absorption test was used to determine the change of transmission performance.At the same time,the relationship between healing mechanism and the change of transmission performance under different healing environments was analyzed.Thirdly,the microscope observation test was used to determine the change of crack width,and the healing tendency of specimens within encapsulated shale pottery sand was studied.(3)The law of the limit generation of healing products generated with the amount of shale pottery sand and the length of crack was revealed,and the healing potential of encapsulated shale pottery sand in cement-based materials was evaluated.This part was based on the relevant knowledge of integral geometry and geometric probability and certain basic assumptions.First of all,the probability formulas of crack and shale pottery sand in two-dimensional area under different intersecting states were established.Afterwards,combined with some experimental parameters in the encapsulated process,the theoretical calculation value of the amount of healing products generated by a shale pottery sand was obtained.Finally,the formula of the limit generation of healing products in any cross section was established to explore its change rule under different pottery sand dosage and crack length.