Study On Mechanics And Durability Of Filling Material For Expansion Device Based On Polyacrylate Cementitious Material

Bridge expansion device is one of the most easily damaged parts of the whole bridge structure.With the rapid growth of traffic in China,the early damage of expansion device is becoming more and more serious.How to effectively improve its service life and reduce maintenance and repair costs is of great significance to the development of bridges in China.In this paper,aiming at the problems of low interfacial bond strength and poor durability of expansion joint concrete,a polyacrylate mortar for expansion joint is prepared.In order to verify whether the mortar is suitable for bridge expansion joint,the mechanical properties and durability of the mortar are systematically studied,and its application in seamless expansion device is calculated and analyzed.The main research results are as follows:(1)The polymerization reaction mechanism of polyacrylate cementitious materials was analyzed,and the composition ratio of polyacrylate mortar was obtained by testing the consistency value and flexural strength of mortar.Based on the flexural and compressive strength tests,the variation laws of the basic mechanical properties and polymerization time of polyacrylate mortar with different initiator dosages were obtained.(2)Based on the uniaxial tensile test,the changes of tensile strength and elongation at break of polyacrylate gelling materials with increasing initiator dosage were obtained,and the tensile stress-strain curves of gelling materials with different initiator dosages were analyzed;the effects of initiator dosage and temperature changes on the tensile properties of polyacrylate mortar were investigated,and the tensile strength and elongation at break of polyacrylate mortar with different initiator dosages and temperatures were obtained.(3)Based on the tensile bond test,the effects of initiator dosage,temperature variation and interface immersion time on the bond performance of polyacrylate mortar and substrate were studied.The bond strength of polyacrylate mortar and substrate under different test conditions was obtained,and the variation law of bond strength with different test conditions was analyzed.The reason for the difference in tensile bond strength under different initiator dosages was analyzed from the microscopic perspective by SEM scanning electron microscopy.(4)The durability test of polyacrylate mortar was carried out,and the effects of different initiator dosage on water absorption,frost resistance and chloride ion permeability of mortar were studied.The reasons for the differences in frost resistance and chloride ion permeability between polyacrylate mortar and ordinary cement mortar were analyzed.(5)Based on the finite element software,the application of polyacrylate mortar in the seamless expansion device was calculated and analyzed.The stress and deformation characteristics of polyacrylate mortar under different load positions are discussed when the temperature variation and concrete shrinkage and creep lead to the tensile or compressive state of polyacrylate mortar.The stress variation along the bridge direction is analyzed,and the feasibility of the application of polyacrylate mortar in the expansion device is verified.