Study On Concrete Surface Hardening And Repair Materials

In recent years, with the large-scale infrastructure construction, the construction industry and transportation industry develop rapidly. The reinforced concrete structure has become the main body, the quality of concrete surface layer of buildings and traffic engineering has gradually aroused concern and attention of the industry. Due to the problem of material and construction, many defects such as structure surface cracking, lack of rebound strength, skin, powder, holes, voids, coarse aggregate exposure are threatening building use and safety, especially in the harsh environment of bridge, tunnel and other structures. Steel corrosion happened in concrete because of external corrosion. Cracks and holes of road gradually increased due to various reasons such as the impact of the volume stability, subgrade settlement, design problems and overloading of vehicles which affecting driving safety and comfort. The surface quality of concrete is very important for the function and durability of the structure. It has very important engineering significance and academic value for the study of concrete surface strengthening and repairing technology.This paper is aiming at concrete surface strengthening and repairing material system. Strengthening material is prepared for concrete surface without crack and failure. The principle is using solvent to form a film at the surface of concrete, increase the density of surface by internal penetration crystallization, hindering water evaporation, limiting harmful media intrusion and improving the surface quality. The surface repair material is mainly study polymer modified mortar which has high bonding strength and good volume stability.The effects of surface strengthening material on surface properties of C30 and C50 concrete are studied. Experiments focus on the effect of water absorption, carbonation, corrosion resistance, corrosion resistance and microscopic test, etc.. Through a lot of experiments, it is concluded that the water solid ratio is 1:5 magnesium silicate and 1:4 water glass double component surface strengthening material and 1:20 aluminum sulfate single component surface strengthening material have good effect. Water absorption rate is lower 1% on average than the test block without surface treatment, carbonation reduce 3mm and corrosion resistance coefficient increased more than 10% and rebound strength increased more than 3Mpa, microscopic test showed that two kind of Strengthening material penetrates the surface of the concrete pore and form silica gel, Ettringite crystal and plug the pores, so that compact surface layer of structure. By the experiments in the laboratory to determine the reference group mix proportion of concrete surface repairing material. the proportion of cement and special admixture is 8:2, cement sand ratio is 1:1 of first group, the proportion of cement and special admixture is 9:1, cement sand ratio is 1:1.5 of second group. The results show that the best dosage of carbon fiber is 3%; types of polymers and the best ratio respectively: VAE1350 emulsion, powder 2350 polymer binder ratio is 5%, powder 4036 polymer binder ratio is 10%. The flexural strength of three kinds of polymer modified mortar is higher 5MPa than the reference group on average. There are some advantages of high bonding strength, good volume stability, no shrinkage cracking. In addition, the properties of fine stone concrete adding polymer mechanical can meet the requirements of specification, and have feasibility on actual pavement repair technology.