Preparation And Performance Study Of Epoxy Resin-cement Composite Repair Material

Epoxy resin is a polymer containing at least two epoxy groups in the molecule.When compounded with cement,it shows the advantages of high strength,strong bonding and excellent corrosion resistance and has a broad application prospect in the field of building repair.Two new types of epoxy resins-oil-based epoxy resin suitable for underwater and water-based epoxy resin compatible with cement concrete were designed and synthesized for both underwater or wet environment and superstructure repair,and a series of basic and applied research on epoxy resin synthesis method,preparation technology and performance of epoxy resin-cement composite repair material were carried out.In order to improve the adhesion and drainage of the epoxy resin to the wet interface and to achieve good bonding between the old and new interfaces,the epoxy resin for underwater repair was synthesized by introducing the hydrophobic components such as phenol and formaldehyde into the epoxy resin.On this basis,modified epoxy mortar for underwater repair was prepared by introducing coupling agents,powders,fibers and sand,and its preparation technology and key performance indexes were obtained.For superstructure repair,based on the principle of similar compatibility,hydroxyl group,ether bond hydrophilic group and bisphenol A chain segment were introduced into aliphatic amine to synthesize a good hydrophilic epoxy resin curing agent,which has good self-emulsifying property when used in combination with epoxy resin;the developed self-emulsifying water-based epoxy resin was used to compound with concrete,and water-based epoxy resin-concrete composite repair materials with different poly/ash ratios were prepared.The mechanical properties and durability of the composite repair materials were explored,and the performance development rules and key performance parameters of the composite repair materials were clarified.The main innovative conclusions of this thesis are as follows.1.After curing in water,the oil-based epoxy resin for underwater repair has a compressive strength of 123.7 MPa,a tensile strength of 28.1 MPa,and a positive tensile bond strength of 2.8 MPa to concrete;the optimal ratio of underwater repair epoxy mortar is mastic:powder:fiber:coupling agent:sand=150:300:5:2:300（wt.%）.At 25℃,the flow of epoxy mortar is 165-190 mm,the compressive strength after underwater casting can reach 70 MPa,the tensile strength reaches 20 MPa,the highest bond strength reaches 4.5 MPa,and the cohesive damage for concrete,the impact abrasion resistance reaches 3.3-4.2 h/（g/cm²）,the coefficient of thermal expansion is47.15×10^-6/℃.2.After compounding with concrete,the toughness,flexural strength,tensile strength,bonding strength and durability of concrete increased significantly with the increase of poly/ash ratio;the axial compression toughness ratio of waterborne epoxy-concrete increased from 0.15 to 0.90,an increase of 500%;flexural strength increased from 6 MPa to 9.16 MPa,an increase of 52%;tensile strength increased from 3.21 MPa to 5.4 MPa,an increase of 68%;the mass loss rate was only 0.7%after 300 freeze-thaw cycles.to 9.16 MPa,an increase of 52.4%;the tensile strength increased from 3.21 MPa to 5.4 MPa,an increase of 68%;the mass loss rate was only 0.7%after 300 freeze-thaw cycles.However,the compressive strength and elastic modulus of the water-based epoxy-concrete composite repair material decreased.