Research And Application Of Ground Surface Repair Material In Low Temperature Environment

In order to solve the problem of the repair of ground surface under low temperature environment,the article describes the types of concrete ground damage and repair materials.For the common repair materials can't be applied to the shortcomings of repair under low temperature environment,a rapid repair material with low temperature resistance,high early strength,wear resistance,small shrinkage rate is studied.At the same time,the bond strength between the ground repair layer and the ground damage layer is analyzed,and the repair method of the ground surface layer under the low temperature environment is proposed.Through the performance test of the three kinds of repair materials,it is found that when the retarder dosage is 4%,the setting time and the fluidity of the phosphate quick repair material is the best.The content of retarder in the rapid repair material of sulphoaluminate is 0.8%,the setting time and fluidity is better.For the ordinary silicate repair material,the setting time is relatively slow,but the fluidity is better.The mechanical test show that the mechanical property of phosphate quick repair material is the best,and the compressive strength at 1h is 31.2MPa after being cured at-18?.The mechanical property of ordinary silicate repair material is the worst,the compressive strength at 28d is 20.4MPa after being cured at-18?;Compared with curing 7days' sulphoaluminate rapid repair material,the strength of the repair material for 14d is lower.After the mechanical test,the initial determination is using phosphate rapid repair material as a repair material in low temperature environment.Then the durability test is carried out,according to the frost resistance test of the phosphate rapid repair material,the frost resistance performance is best after curing at 0?,and the frost resistance performance is the worst after curing at-18?.By changing the fiber content of the phosphate rapid repair material,it can be found that the phosphate rapid repair material with fiber content of 1.8 kg/m3 has the best frost resistance,the phosphate rapid repair material with fiber content of 0.9kg/m3 has the worst frost resistance.In the meantime,the adjustment of the fiber content in the compounding ratio of phosphate rapid repair material to 1.8kg/m3 has little effect on the compressive strength and flexural strength.After curing at-18?,the compressive strength and flexural strength of the specimen for 1h are 32.7MPa and 5.5MPa.The compressive strength and flexural strength of specimen for 28d are 63.8MPa and 10.1MPa.Different low temperature curing environment have little effect on the abrasion resistance and the shrinkage rate of the phosphate rapid repair material,both of which can meet the requirements of the ground surface repair.According to the bonding mechanism and failure mechanism of concrete bonding surface,the main factors affecting the bond strength of concrete bonding surface are summarized as follows:the strength of old concrete,the type of rapid repair material,interface roughness,interface treatment methods,construction environment and maintenance measures.Using phosphate rapid repair material and ordinary silicate cement mortar for the anti-bending test,by ordinary silicate cement mortar block section to take a different cutting depth,when the average depth of cut is 3mm,the bond strength reach 5.3MPa after being cured for 28 days,and the repair requirement of the ground surface is satisfied.Then the construction method and quality control measures of ground surface repair under low temperature environment are put forward by analyzing the damage pattern of ground surface and choosing the appropriate rapid repair material.The rapid repair material applies to the actual project and determines the feasibility.