Study On Property Of Epoxy Mortar For Repairing Marine Structures

China has a long coastline and a large number of concrete structures in the marine environment.However,due to the influence of the environment in which the concrete structures are located,the poor construction quality or improper design,the service life of marine structures is generally less than 30 years.In order to ensure the safe operation of marine structures and the exertion of engineering benefits,it is necessary to carry out maintenance and reinforcement at the initial stage of damage.Epoxy mortar has good bonding property and corrosion resistance and can be used to repair marine structures.The mechanical property of epoxy mortar is susceptible to the type and amount of each component,through theoretical analysis and selection of raw materials,The effects of the amount of filler,the type of filler and the ratio of sand to glue on the mechanical property and fluidity of epoxy mortar were studied to determine the mix proportion of epoxy mortar.In order to analyze the repair performance of epoxy mortar,the effects of interfacial moisture degree,interface agent and interfacial erosion degree on the bonding property of epoxy mortar for repair were studied by testing the bonding flexural strength of epoxy mortar after curing for 7 days,among them,the wetness of the interface is divided into dry,saturated surface and 10 minutes of dryness in a room temperature environment with a humidity of 60%;The degree of interface erosion is changed by soaking cement mortar specimens in natural seawater through dry-wet cycles.The mechanical properties of epoxy mortar are also affected by temperature,the temperature sensitivity of epoxy mortar was studied by testing the mechanical property of epoxy mortar at 20 ?,40 ?,60 ? and 80 ?,and combined with differential scanning calorimetry(DSC)test to determine the upper temperature limit of epoxy mortar with appropriate properties.The results show that:(1)The mechanical property and fluidity of epoxy mortar are significantly affected by the amount of filler,the type of filler and the ratio of sand to glue.Comprehensive analysis of the mechanical property and fluidity of epoxy mortar,and the mix proportion of epoxy mortar is determined: The ratio of glue A to glue B is 3:1;The sand-cement ratio is 3:1;The ratio of sand to filler is 5:1;The filler can be selected from cement,secondary fly ash or S95 slag.(2)The bonding property of epoxy mortar is significantly affected by the degree of interface moisture,but the interface agent and the degree of interface erosion have little effect on it.The bonding performance of the epoxy mortar decreases as the moisture level of the bonding surface increases.When the bonding interface is dry,the bonding flexural strength is above 9 MPa,all three fillers can be used to prepare epoxy mortar;when the interface is wet,the cement is selected as the filler and the interface agent is not used,and the bonding effect of the epoxy mortar is the best,(3)With the increasing of temperature,the strength of epoxy mortar gradually decreases,and the deformation capacity first increases and then decreases.The mechanical property of epoxy mortar is significant lost at 60 ?,with the compressive strength decreasing by about 53% and flexural strength decreasing by about 55%.Moreover,it can be seen from the DSC test that the glass transition temperature of epoxy cured product is low,but the heat resistance of epoxy cured product can be significantly improved by adding filler in the epoxy glue.Therefore,it is determined that the upper limit of using temperature of the epoxy mortar should not exceed 60 ?.In this paper,the mix proportion of epoxy mortar is optimized,and the bonding property and temperature sensitivity of epoxy mortar are studied,which can provide a certain reference for repairing marine structures.