Research On The Effect Of Different Interface Agent To The Second Instar New And Old Concrete Bonding

This thesis choose three kinds of interface agent and three kinds of common concrete to do the experiment of new and old concrete bonding in the second instar,explore the bonding effect and the applicability of the three kinds of interface agent,and analyze the hydration mechanism in the effect of the interface agent in the interface of new and old concrete. The equivalent coefficient β is proposed for the first time. The main contents and conclusions are as follows:(1)Choose the three kinds of common concrete, which are portland cement, slag cement and composite cement, as the materials of the testing C30 concrete. The three kinds of testing interface agent are cement paste, cement paste mixed with fly ash and cement paste mixed with new material TG-1 consolidation agent. Prepare for new and old concrete bonding experiment by testing the time of the second instar of the three kinds of concrete.(2)Experimental results of the effect of the three kinds of interface agent that are used on the three kinds of new and old concrete bonding show that: The effect of cement paste interface agent enhances as it increases water-cement ratio. The regularity of the effect of cement paste mixed with fly ash on the interfacial strength of new and old concrete is not obvious. The effect of cement paste mixed with TG-1consolidation agent enhances as the the content of TG-1 consolidation agent improves. The best applicability are the cement paste mixed with 50% TG-1consolidation agent used on Portland cement concrete and composite cement concrete bonding, and the cement paste with 0.3 water-cement ratio used on slag cement concrete bonding.(3)In order to compare the bonding effect of different types of interface agent to different concrete, the equivalent coefficient β is proposed for the first time. It is the ratio of new and old concrete bonding strength and the splitting tensile strength of reference test blocks, which is the effectiveness of bonding strength.(4)Analysis of the hydration mechanism in new and old concrete bondinginterface shows that cement paste interface agent enhances the bonding strength by improving the microscopic structure of the interfacial transition layer. And cement paste mixed with fly ash and cement paste mixed with TG-1 consolidation agent facilitate the hydration reaction in the bonding interface to improve the adhesive strength of the interface mainly by chemical action.