Study On Bond Capability Of Young And Old Concrete With Mechanical Joint

The repair and strengthening of concrete structure has become an important engineering domain .So the study of adhesive performance of young and old concrete has far-reaching meaning for the security of repaired structure.Where the shoe pinches of the repair success is all right combination of young and old concrete.Presently,most of the researches inside and outside country made the two into one to against force through felt.In practice,however,it can't obtain ideal bond capacity only depend on adherence.Thus,this paper bring forward a young method to make up the lack of felt capacity-use mechanical joint element to link young and old concrete.In fact,the adherence of young and old concrete belongs to the adherence research work of bimaterial.The simulation calculation shows that in the range of criterion provision of young and old concrete that the formula for calculating the splitting tensile strength of a monolithic concrete specimen can be used to a concrete specimen of young and old concrete when the difference of elastic modulus of young and old concrete is small.The cleavage strength test has been carried out to investigate the effect of pour direction for the strength of specimen without mechanical joint element ;the effect of mechanical joint element for the cleavage strength;the effect of different materials which were used to embedding bars for the cleavage strength. All the interface of specimens we mentioned above had the same roughness.The reasons of different pour direction effects for the cleavage strength has was analyzed,so did the mechanism of mechanical joint element in the cleavage test.In the situation of same roughness interface,compared the shear strength of specimens with mechanical joint element and that of without;Compared the shear strength of specimens with adhesive agent and without adhesive agent when there were mechanical joint element in the specimens. Compared the shear strength of specimensthat was made of young and old concrete and which was monolithic.The load-stain curve of bar was obtained in the shear strength test. The mechanism of mechanical joint element in the shear test was analyzed. Strengthen mechanism of adhesive agent-expand cement paste.