| Concrete material,as the most common building structure material,has been widely used in structural engineering such as buildings,bridges,roads,airports,dams,and reservoirs since its inception.Due to humidity,temperature,shrinkage,uneven settlement and load,the concrete structure will cause damage to the components and cause cracks.This greatly reduces the durability of concrete.Although the micro-cracks will not have a great impact on the structural components in the early stage,if the cracks continue to develop and extend,it will inevitably have a greater impact on the durability,impermeability,structural safety and stability of the structure,and even affect the people’s health.A major threat to life and property safety.In this paper,the synthesis process of polymer material repairing agent,its influence on the mechanical properties of cementbased materials and the repairing properties of repairing agents on cement-based materials are studied.（1）In this paper,a polymer material based on environmental impact was developed and designed,and the water absorption performance and permeability of the polymer material repair agent were analyzed;the results showed that the polymer material repair agent can absorb 51.34 times its own weight in distilled water,and can absorb water repeatedly after drying;in the simulated pore solution,due to the difference in ion concentration inside and outside the solution,the water absorption effect is less than that in distilled water;the permeability coefficient of the polymer material itself is close to that of fine sand;It is confirmed by infrared,solid-state nuclear magnetic resonance,thermogravimetric test and other characterizations that the polymer material is a polymer,so the water molecule monomer can exist in the three-dimensional grid inside the polymer;（2）Considering the workability of the polymer repair agent and the cement-based material,and whether other chemical reactions will occur during the cement hydration process,this paper studies the cement cleaning agent mixed with different amounts and particle sizes of the polymer repair agent.The water consumption of the standard consistency of the slurry,the compressive strength of the cement paste,and the XRD analysis of the test blocks after the hydration of the clean paste test blocks in different curing time periods;The water consumption for standard consistency of the slurry and the compressive strength of the cement paste have a great influence.The influence of the standard consistency water consumption and the strength of the slurry test block can be ignored;the XRD analysis results of the 3d and 56 d terminated hydration products mixed with different contents of the polymer repair agent show that the polymer material repair agent is in the process of hydration with cement.no new products will be generated in（3）The self-healing research object in this paper is the mortar test block.The addition methods of three polymer material repair agents are designed,and the cement mortar test block is made to study the influence of the polymer repair agent on the mortar test block;respectively,the fixed water-cement ratio,Additional supplemental water,fixed water-cement ratio and additional water-reducing agent.In the test,the effective water-cement ratio of the test is guaranteed to be the same by controlling the initial fluidity of the mortar to be the same.The results show that the compressive strength and flexural strength of the mortar test block also decrease with the increase of the content of polymer materials.（4）The research on self-healing technology of cement-based materials in this paper is to test the change of crack width,internal ultrasonic wave speed and capillary water absorption after prefabricating cracks on a mortar test block of 40 mm × 40 mm × 160 mm to characterize the degree of self-healing;40mm × 40 mm × 40 mm The self-healing effect is characterized by comparing the mechanical strength recovery of 60% and 75% of the compressive strength value of the mortar test block after pre-pressing;the permeability coefficient changes of the cylindrical mortar test block with a diameter of 100 mm and a height of 50 mm after pre-pressing cracks at different ages The self-healing effect was characterized;the dosage of the repairing agent was 0%,0.3% and 0.5%,respectively;the maintenance environment of the mortar test block was tap water environment,p H=12alkaline solution and 3.5% Na Cl solution.The test results show that adding the repair agent has better effects on the repair of cracks,strength recovery and permeability coefficient of the mortar test block,and the effect is even better in tap water and alkaline solution with p H=12.（5）The microscopic analysis test was carried out on the addition of the polymer material repair agent to the cement-based material through the pore analysis test,XRD qualitative analysis and scanning electron microscope test.The results showed that the number of pores inside the test block mixed with the polymer material repair agent was significantly larger.For the test block without adulteration of the repair agent,the internal pores are the main reason for the low strength of the test block mixed with the polymer material repair agent;XRD and SEM analysis infer that the repair mechanism of the polymer material repair agent is physical adsorption,In the process of self-healing of cement mortar cracks,no new chemical substances are generated at the cracks.Only through the physical adsorption of polymer materials,the interface binding between polymer functional groups and the complexation of metal ions,through three effects Interconnected to form a network of substances to repair cracks.The polymer material repair agent can absorb a large amount of water in the environment and expand in the cracks.On the one hand,it can fill the cracks and block harmful substances and ions from entering the cracks,which will weaken the durability of the structure and prevent the further expansion of the cracks.The transport of water deep into the crack promotes the further hydration of the unhydrated cement,which together allow the crack to be repaired.Figure [85] table [21] reference [41]... |
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