Some Influencing Factors Of Properties Of Granite/ Silane Coupling Agent/ Cement Paste Interfacial Layer And Its Modifying Mechanism

Some existed experimental studies indicated that bond strength of new-to-old concrete interface could increase noticeably by coating old concrete surface with silane coupling agent. In the light of this, the idea to increase the durability of large diameter granite aggregate mid-strength concrete by modifying aggregates and cement paste interfacial layer with silane coupling agent was put forward. As the first part of the research programs, the main influencing factors of bond strength and the acting mechanism of granite/ silane coupling agent /cement paste interfacial layer was emphatically studied. Taking pull-off bonding strength and splitting tensile strength of granite/ cement paste interface modified by silane coupling agent as indexes, the influences of the solution consistency of silane coupling agent, temperature and time applied, and mix ratio of mortar materials on bond strength of granite/ cement pasteinterface were investigated through contradistinctive experimental studies. The results showed that bond strength of silane coupling agent modified granite/ cement paste interface had been greatly improved. Rational solution consistency of silane coupling agent, temperature and time applied were suggested. Based on the above experimental studies, silane coupling chemistry and concrete material, a mechanism that silane coupling agent may create chemical bonds between cement paste and granite interface was primarily put forward. Secondly, in order to develop a new technical method for producing mid-strength and durable concrete, large diameter granite aggregates were steeped in a silane coupling agent solution, followed by the mixing of the concrete. The test results showed that the compression strength of the modified concrete increased noticeably. In addition, the co-effect of silane coupling agent, shrinkage reducing admixture and fly ash on new-to-old concrete interfacial layer was primarily studied. Last, the suggestions and prospects for the future research were brought forward.