Study On High Ductility Cement-based Repair Material For Bridge Pier Prepared By Polypropylene Fiber

With the wide application of concrete material in modern civil engineering construction such as construction,bridge and dam construction and the progress and development of science and technology,as the main building material,the performance of concrete material is put forward higher requirements.At present,our country is investing heavily in infrastructure,promote the construction of west,due to the western region of rivers and river twists and turns,fast-flowing,river mud,shifting sand content,river sand and gravel on the hydraulic structures of scores on the surface of the overcurrent caused serious erosion wear of concrete damage,the serious influence the service life of hydraulic structures,It is difficult and costly to maintain hydraulic structures,which consumes a lot of manpower and material resources.Therefore,it is of great importance and practical significance to study a kind of repair material suitable for repairing bridge piers with high strength,high ductility and excellent durability.In this paper,the mechanical properties and durability of high ductility cement-based repair materials are studied,and the main work is as follows:1.Through early tests,it was found that the addition of nano-sio2 further improved the mechanical properties of high ductility cement-based repair materials,but there was an optimal dosage.2.Through orthogonal test,the effects of different silica fume content,microbead content,nano-silica content and fiber volume content on mechanical properties of high ductility cement-based composites were explored.The results show that the material has high compressive strength and ductility.In terms of compressive strength,the content of nano-silica and microbeads are the main influencing factors.In terms of flexural strength,the volume content of fiber and silica fume content are the main influencing factors.For ductility,silica fume content and nano-silica content are the main influencing factors in the range of 2%-3%fiber content.3.Through the electric flux test,compared with the chloride ion penetration grading standard,it can be concluded that the electric flux value of the material is very small,and has excellent impermeability.Orthogonal analysis of the test results shows that the main factors affecting the impermeability of the repair material are silica fume content and microbead content.4.Through self-repair tests under different repair environments,it is found that the repair material has good self-repair ability,and has self-repair behavior in clean water,seawater,acid rain and other environments.The self-repair ability in the repair age of 100d is acid rain environment>seawater environment>clean water environment.5.Summarize the existing erosion wear test methods,through the erosion test and analysis of the test results,the erosion wear process of the repair material is described,the main factors affecting the erosion wear are analyzed,and the influence of single factor on the wear resistance and erosion resistance of the repair material is explored.Compared with C50common concrete,it is shown that the wear resistance and scour resistance of the repair material are obviously better than that of common concrete.6.on the completed research,choose 3 groups has a better comprehensive performance ratio of bonding experiments,summarized the repair materials for splitting tensile test of two kinds of bond failure modes,through the study found that the influence factors of bonding repair materials mainly is the interface roughness,within a reasonable range,splitting the compressive strength increased with the increase of the roughness.Under the condition of the same roughness and grinding depth,the splitting tensile strength of the three groups of cement-based repairing materials is greater than that of C50 ordinary concrete,indicating that compared with ordinary concrete,the three groups of preferred repairing materials all have good bonding properties.7.from the micro-level analysis of repair materials,through SEM found that most of the repair material matrix and the interface between quartz sand is very dense,a handful of repairing material ratio while aggregate-slurry interface bonding is not close,but overall relatively dense,repair materials combine closely,fiber and matrix was pulled off the fiber had obvious stretch marks.By EDS spectrogram analysis,it was found that some microbeads retained a large number of active SiO₂ and Al₂O₃ components,which was due to the low basicity of the system,and excessive microbeads could not fully participate in the reaction in the mortar system,and mainly played a physical filling role...