Performance Of Coupling Agent And Shrinkage Reducing Agent Modified Repair Interfacial Layer Between New And Old Concrete

To significantly improve both strength and durability of repair interfacial layer between old and new concrete, two attempts were firstly put forward in this thesis: (1) A kind of new modified primer would be produced by introducing shrinkage reducing admixture into cement mortar, which may both reduce the shrinkage of the interfacial layer, and lessen the content of large crystal in the repaired interface layer, accordingly, remarkably increase the Van der Waals force of interfacial layer. (2) By virtue of the coupling agent technology in complex materials science, chemical force between repair material and old concrete was produced by means of applying coupling agent to coat old concrete. Homemade shrinkage reducing agent NA-SP and homemade silane coupling agent KH-570 were chosen for a large experimental research. The test results showed that two methods effectively improved both macrostructure and microstructure of interfacial layer, and therefore, significantly improved bond performance. The research overcomes the shortcomings of primers in common use, and breaks through the traditional astriction of absence of chemical bond between new and old concrete. Both macrostructure and microstructure as well as bond mechanism was discussed and some further research advice was put forward.