Preparation And Properties Of Polymer-modified Cement-based Waterproofing And Plugging Materials

In recent years,with the increase of the number and depth of underground structures,the problem of underground structure leakage has become increasingly prominent.Due to the unreasonable design,poor construction quality,change of service conditions and other reasons,many underground structures often have water leakage diseases during the design service life,which seriously affect the beauty and various use functions of the building,and also adversely affects its safety,applicability and durability.In the treatment measures of water leakage diseases,grouting plugging method has been greatly developed and widely used in engineering practice,but the grouting plugging of micro cracks is still one of the engineering problems.At present,the common grouting materials for plugging fine cracks are mostly organic materials.Organic waterproof plugging materials have the advantages of controllable setting time and good grouting performance,but their application is limited by factors such as high cost,low durability,high pollution and toxicity.Inorganic waterproof and plugging materials are represented by cement.Cement materials have simple raw materials,low cost,environmental protection and non-toxic,and excellent durability.However,ordinary cement materials have large particles,which are difficult to inject into fine cracks,and the setting time is relatively long,the porosity of cement stone is high,so they can not effectively block fine cracks.Therefore,in order to solve the problems of high cost,poor durability of organic waterproof and plugging materials,and solve the problems of poor pouring ability,long setting time and high porosity of cement stone,this study uses ultra-fine cement.Firstly,a composite ultra-fine cement-based material with controllable setting time,good flow performance and high mechanical strength is prepared,and then through organic and inorganic composite technology,the organic polymer water-based epoxy resin was added into the composite ultra-fine cementbased materials for modification,and the effects of water-based epoxy resin on the working properties,basic mechanical strength,interfacial bonding strength and impermeability of the composite ultra-fine cement-based materials were studied and analyzed.It is expected that a polymer modified cement-based waterproof and plugging material with good performance and meeting the needs of engineering can be prepared.The main research contents and conclusions are as follows:(1)A composite ultra-fine cement-based material is prepared by compounding superfine ordinary Portland cement and self-grinding fast-hardening sulfoaluminate cement,and adding admixtures such as expansion agents for modification.The influence of sulfoaluminate cement content on setting time,fluidity and basic mechanical properties of composite ultra-fine cementbased materials was analyzed through experimental research.The research results show that sulfoaluminate cement can play a role in promoting setting and early strength in composite ultrafine cement-based materials.The setting time of composite cement paste gradually shortens with the increase of sulfoaluminate cement content.The early strength of the composite ultra-fine cement-based material increases rapidly,which leads to a gradual decrease in the initial flow properties of the slurry;with the increase of sulfoaluminate cement content,the later mechanical strength will gradually decrease.When the content is 18%?20%,the mechanical strength of composite ultra-fine cement-based materials will shrink backward.After research and analysis,it is determined that the optimal dosage of sulfoaluminate cement is 15%.(2)A polymer modified cement-based waterproof and plugging material is prepared by adding water-based epoxy resin into the above-mentioned composite ultra-fine cement-based material for optimization and modification.The influence of water-based epoxy resin content on the working performance,basic mechanical strength,interfacial bond strength and tensile deformation of the modified composite ultra-fine cement-based material was studied and analyzed.The research shows that the incorporation of water-based epoxy resin will prolong the setting time of the modified composite ultra-fine cement material,and the fluidity,flexural strength,interfacial bonding strength,tensile deformation and tensile strength of the material can be improved with appropriate content,but the compressive strength will be reduced.(3)The modification law of water-based epoxy resin on the shrinkage,expansion and impermeability of modified composite ultra-fine cement-based materials was explored and analyzed.The results show that adding an appropriate amount of water-based epoxy resin will make the overall structure more compact and block the channels for water evaporation and infiltration,thereby reducing the drying shrinkage of the polymer modified cement-based waterproof plugging material and improving the impermeability of the material.performance.(4)The groutability of polymer modified cement-based waterproof and plugging materials was studied.The results show that the raw materials selected in this study have good groutability for cracks with width greater than 0.35 mm.