| The existence of the concrete structure crack will affect its durability, severe cases can also affect the bearing capacity of the structure. Therefore, in most cases need to repair the concrete cracks. Due to a variety of crack repair techniques commonly used, makes the application of crack repair has certain complexity, and part of the project due to the unreasonable repair technology selection is chosen in secondary cracks. It is necessary to comparative analysis of various crack repair technology, choose the optimal ratio of method, and then provide a reference basis for crack repair projects. In this paper, based on the traditional epoxy resin formula, 6 groups of epoxy resin ratio were designed, and the best ratio of the two groups was optimized by experiment. To explore the improvement in mechanical properties of the concrete member crack after epoxy grouting,concrete members with different levels of width, depth, were prepared by the method of interpolation of copper,and then tested the relevant compression strength as well as bending strength performance. At the same time, through the test of beam bending cracks are patched by the method of low pressure grouting at low speed and compression test, The cracking load as well as ultimate load of the reinforced concrete beam before and after repairing are tested. The experimental results showed that:(1) To achieve ideal effect of grouting repair,the initial viscosity and bonding strength of epoxy resin grouting material should be considered. This epoxy grouting material has many advantages,such as low viscosity, high permeability, high bonding strength and the strong operational time. Therefore it can fill different levels of crack width and depth.(2) The influence of the cracks on concrete mechanics performance, not only related to the crack width, depth are also associated with concrete grade. Width as well as depth of concrete increases, the strength loss of concrete increase; The increase of concrete strength grade, strength loss rate is on the decline.(3) The results show that the epoxy grouting material with seam concrete specimen mechanical properties have better repair effect, restore and improve the related mechanical properties of the specimens. Repair effect besides associated with grouting material, also with the concrete crack depth, width and strength grade of concrete. Epoxy grouting before and after repair, the compressive strength failure mode does not change, but the recovery rate of the strength can reach more than 80%; Flexural strength failure forms are diversified with strength grade of concrete crack depth and width, but the mode is brittle failure. The new fracture is not line up along the original cracks, but next to the original crack of concrete, and the strength recovery rate is close to more than 100 %.(4) Water penetration test piece are repaired with DN type epoxy resin grouting material, and the density of the concrete component is better than the standard one. Seepage rate is greatly reduced, and its anti-permeability performance is improved.(5) The results show that beam bending failure mode is the typical optimal muscle damage and is not changed after the epoxy resin grouting repair, and each point on the section meet the flat section assumption. The section stiffness of reinforced concrete beam, the cracking load, ultimate load and even the deflection are a certain degree of recovery or even increase after the epoxy resin grouting repair. The repair effect of the DN type epoxy resin grouting material is better than the one of the GR type epoxy resin. |
PDF Full Text Request