Applicability Research On Epoxy Materials Used To Wet And Underwater Concrete Repairing

More hydraulic structures built in the early days of our country,so there are some defects more or less,even new projects have seen varying degrees of damage in recent years,especially underwater structures.There is abundant rainfall and more groundwater in the south of China,The whole concrete matrix of underground works causes erosion damage because of the long-term flowing water affected.As these disruptions affect the stability of the structure and the safety of the entire building,repairs are urgently needed.But because the structure is in an underwater or humid environment,the repair needs to be done in a wet or underwater environment.This paper is mainly based on the erosion damage of concrete in tailing pond of Fengtan Hydropower Station,and analyzes the three types of damage of underwater concrete:erosion damage,crack damage,leakage damage,and the use of epoxy resin materials to carry out different damage types of concrete indoor simulation repair.In this paper,a large number of laboratory experiments and simulation techniques have been carried out on the performance of the materials,especially the engineering practice,and the following aspects are studied:(1)Study on the performance of Underwater Epoxy Mortar.The test results show that the material has an underwater bonding strength of over 2.50MPa,and its underwater adhesion strength is basically the maximum at 3.50MPa after seven days.After the impact of the steel bead 72h,the maximum abrasion resistance of the specimen is 847.80 h/(kg/m2),the new type of epoxy mortar does not produce discrete phenomena in the static water,the permeability level is greater than P12 and the permeability resistance is good.(2)Study on the properties of epoxy grouting materials.The test results show that the initial viscosity of the grouting is 16.00 MPa·s at 23?,the operational time and the initial setting time are 2h and 6h,respectively,and the bonding strength to underwater concrete reaches 2.90 MPa,and the compressive strength of the cured products of 49.15MPa.(3)Process on the underwater concrete indoor repair.Epoxy mortar is used to repair the concrete pit,and the core can be found to be cemented to the concrete.Using epoxy grouting material to repair cracks and leakage parts,repair and found defects has been effectively fill,no obvious cavity and crack,increased the resistance in the process of water penetration,improve the overall permeability performance.(4)For this problem that erosion and cracks in the lower section of the overflow surface of a hydropower station in Hunan,A new type of epoxy mortar was developed to repair the damaged parts by combining the corresponding construction technology.After the repair,the patches were levelled and no cracks and cavitation were observed.Due to limited time,field applications are currently only performed in wet environments and field applications are required in complete underwater environments to fully affirm materials and processes.