| With the development of reinforced concrete structures,buildings such as high-rise buildings,cross-sea bridges,dams and hydropower stations have been erected.However,due to their own nature and external environment,they bring different degrees of crack damage to the structure.The reinforcement materials improve the secondary safety and durability of existing concrete structures.Water-based resins and curing agents,etc.are made into EAU（Eco-friendly Acrylics Unity）concrete crack repair materials,which have the advantages of both water-based epoxy and water-based acrylic resins and do not contain VOC（volatile organic compounds）emissions,and are green materials.In this paper,the mechanical and repair properties of the new water-based repair material are studied.The main research contents are as follows:（1）When the ratio of curing agent:water-based resin:superfine cement=1:3:4 and the content of defoamer is 0.6%,the combination of setting time,flow,flexural strength and compressive strength is optimal,which is the best ratio of the new water-based EAU concrete repair material.The repair material with this ratio was applied to the fractured surface of concrete test block,and the bond flexural strength and tensile bond strength were measured to reach the strength of C40 concrete.And the flexural strength can reach 88%and above before repair.（2）The repair material was applied to hematite concrete in precast cracks,and the mean and standard deviation of tensile strength ftand fracture toughness KICbefore and after repair were determined using the normal distribution method based on the virtual crack extensionΔafic=1.0dav,and the comparison yielded a significant repair effect with a 16.9%increase in mean tensile strength ftand a 44.0%increase in mean fracture toughness KIC.（3）PFC2Dis used to establish a discrete element numerical model that can reflect the matrix,aggregate,and interface transition zone.The simulation results better fit the test range and damage mechanism of concrete loading before and after repair.It is shown that it is possible to simulate the discrete properties of hematite concrete composed of fine aggregates before and after repair,as well as the discrete properties of plain silicate concrete composed of both coarse and fine aggregates,verifying that discrete models can be used for concrete.（4）To verify the universality of the proposed discrete model application,the three-parameter Weibull distribution method was used to statistically measure the dispersion of tensile strength and fracture toughness of PMMA bone cement.Based on the statistical properties of ftand KICminimum,the lower safety control index of PMMA bone cement is obtained.And the complete prediction curve of PMMA bone cement fracture with 95%reliability is obtained. |
