Study On The Bonding Performance And Interface Simulation Of Polymer Modified Cement Pavement Repair Mortar

With the increasingly heavy traffic loads,the concrete structure of highway roads,which has high strength,good durability,strong resistance to ultraviolet radiation,and high safety,is being damaged,and the task of repairing road surfaces is becoming increasingly heavy.The bonding strength between the new and old materials is one of the most critical points for repairing cement concrete road surface damage.This article aims to develop a high-viscosity and efficient polymer cement road repair mortar.In this study,styrene-butadiene rubber emulsion（SBR）and acrylic acid emulsion（AE）were used as modifiers,and an orthogonal test was conducted to obtain a polymer-modified cement road repair mortar with better comprehensive properties.Furthermore,the interfacial bonding properties between new and old materials were studied,and interfacial bonding simulation was conducted.The main research contents and conclusions are as follows:（1）The working performance and mechanical properties of SBR and AE single-modified repair mortars were studied.The experimental results showed that when the C/R was 0.1 and the defoaming agent dosage was 0.6%,the flowability and flexural strength of AE-modified repair mortars were higher than those of SBR-modified repair mortars and ordinary cement repair mortars.The compressive strength of the SBR-modified repair mortar was stronger than that of the AE-modified and ordinary cement repair mortars.（2）An L₁₆ orthogonal test was used to study the macroscopic and microscopic properties of SBR-AE copolymer-modified repair mortars and to obtain the optimal polymer-modified cement repair mortar ratio.The results showed that the water-cement ratio was the most important factor affecting the working performance and compressive strength of the repair mortar,while the polymer-to-cement ratio and AE/SBR had the greatest impact on the flexural strength and bonding strength of the repair mortar.Microscopic analysis showed that the C-S-H gel structure in the SBR-AE-modified repair mortar was more continuous and uniform,indicating better bonding properties.The optimal polymer-modified cement road repair mortar ratio was obtained:W/C=0.45,L/S=1:2,C/R=0.15,and AE/SBR=1:1,with the dosage of DF is 0.6%,and the dosage of SP is 0.8%.（3）The effects of interfacial humidity and interface grooving treatment on the tensile bonding strength between polymer-modified cement road repair mortar and old concrete substrate were studied.Load-displacement curve fitting analysis and microscopic analysis were carried out to investigate the interfacial bonding properties.The experimental results showed that the old concrete interface was in a wet state,and the bidirectional grooving treatment method could make the connection between the polymer-modified cement road repair mortar and the old concrete substrate more compact and had higher bonding strength.Microscopic analysis also revealed that cracks occurred at the interface of dry or humid states,while the boundary line between the new and old materials in a wet state was less obvious.（4）A finite element method was used to establish the bonding model of polymer-modified cement road repair mortar and old concrete substrate.The experimental results showed that the stress at the interface was significantly higher than that at other positions in the sample when there was no treatment.The bidirectional grooving treatment method could better disperse the stress and bear larger loads.In addition,the load-displacement curves of different samples were consistent with the actual test results,indicating that the model could accurately reflect the actual situation.