Study On Performance Of Cement Repair Mortar Modified By Epoxy Resin

Cement-based material is a kind of porous,multiphase,hard and brittle materials.Under the action of external loads or in harsh use environment,the internal and surface of cement-based materials are prone to peeling,cracks,holes and other damages,resulting in a serious shortening of service life of cement products,while causing economic and property losses,it may even threaten the safety of people's lives and property.However,timely use of repair materials to repair cracks and defects in cement matrix is an effective method to improve the service life of cement-based materials.In this paper,according to the demand of cement repairing materials,epoxy resin modified cement mortar with better performance is put forward as repairing material,and the influence of epoxy resin on the properties of cement mortar and its mechanism were studied.The main contents of this paper are as follows:(1)The effect and mechanism of epoxy resin emulsion on hydration of cement mortar were studied,and the effects of epoxy resin on cement setting time,hydration process and hydration product were studied.The results showed that epoxy resin prolonged the setting time of cement paste,but accelerated the hydration reaction rate of cement during curing,and increased the production of hydration products.(2)The influence of epoxy resin emulsion on the mechanical properties and working performance of cement mortar was studied.The results show that epoxy resin can improve the fluidity,water absorption,bond strength,ion erosion resistance and shrinkage resistance of cement mortar,but reduce the compressive and flexural strength and apparent density of mortar.(3)The effects of tributyl phosphate and solid silicone defoamer on mechanical properties,fluidity and pore structure parameters of epoxy resin modified mortar were studied.The experimental results show that both defoamers can improve the apparent density and mechanical strength of the modified mortar,and the defoamers can reduce the porosity and pore size of the hardened modified mortar,thus making the structure of the modified mortar more compact,thus achieving toughening and reinforcing effect.(4)The effects of basalt and polypropylene fibers on the basic mechanical properties and fluidity of epoxy resin modified cement mortar were studied.The results show that the fibers hinder the free movement of solid particles in the slurry,which reduces the fluidity of the mortar;the basalt fibers with higher strength can enhance the mechanical properties of epoxy resin modified mortar better,while polypropylene fibers are not suitable as reinforcing fibers of the system.