Research On The Influence Of Interface Characteristics On Bonding Performance Between New Concrete And Old Pavement

Due to the strong brittleness and large shrinkage of the surface layer of cement concrete pavement,the deformation coordination with the underlying layer or structural layer,and the poor bonding performance between layers,it is easy to cause the generation and expansion of reflective cracks,resulting in the formation of transitional broken layers between layers,failing the pavement before reaching the specified service life.In this paper,the bonding modified cement-based interface agent is configured to improve the bonding performance between the cement concrete pavement and the lower concrete layer in order to improve the performance of the pavement structure,and the influence of the material composition,interface characteristics and material characteristics of the new concrete pavement on the bonding performance between the cement concrete pavement and the lower concrete layer is studied.The main research work carried out in this paper and the corresponding research results are as follows:1.To study the influence of materials composition of interfacial agent on its own performance and interlayer bonding performance,and put forward the formulation of interfacial agent suitable for spraying and manual brushing respectively.Through the test and theoretical analysis,it is concluded that when the water-cement ratio is 0.23 and the sand-cement ratio is 1.3,better mechanical properties can be obtained.The addition of styrene-butadiene emulsion and ethylene powder significantly improves the mortar strength including the bonding strength of polymer-modified cement quartz SBRmodified cement quartz mortar is more suitable for improving the interlayer bonding performance of cement concrete pavement.2.Through the interfacial shear test and core pull-out test,the influence of interfacial characteristics on interlayer bonding performance including interfacial agent brushing thickness,mixed brushing,waiting time after brushing,and interfacial treatment parameters is studied.The results show that the influence of different fluidity brushes shing with the same interfacial agent on interlayer bonding performance is quite complex.In general,the interlayer bonding reinforcement agent with a single fluidity is comparable to that with brushing.Most of the interfacial agents used for mixed brushing can enhance the bonding properties between the interfacial agents with high and low fluidity.The coating thickness of the interfacial agent should not exceed 2 mm.With the increase in time delay for placing new concrete after applying an interfacial agent,the interfacial bonding property decreases exponentially A better bonding effect can be obtained by placing new concrete immediately after applying interlayer bonding reinforcement.Increasing the groove spacing can improve the interlayer bonding performance of old and new concrete,but the groove spacing should not be less than 10 mm.3.By interfacial shear test and core pull-out test,the influence of new concrete type and a maximum diameter of coarse aggregate on interlayer bonding between new concrete and old pavement is studied.Through theoretical analysis,it is concluded that:single but audience styrene emulsion in new concrete can reduce early interlayer bonding strength,but has little influence on mid-late bonding strength.Single steel fiber can effectively improve interlayer bonding performance.Mixing steel fiber with styrenebutadiene emulsion is more suitable to enhance the interlayer bonding performance between new concrete and old pavement.The interlayer bond between new concrete and old pavement can be enhanced by properly reducing the maximum diameter of coarse aggregates in new concrete.