Study On The Performance Of Low-Shrinkage,High-Toughness Hybrid Fiber-Reinforced Bridge Deck Paving Concrete

In the process of opening the bridge to traffic,the bridge deck paving often appears prematurely damaged,cracked and other diseases,which greatly reduces the safety of the bridge structure and greatly affects the driving experience.At the same time,the frequent maintenance and reinforcement of the bridge deck paving structure and the t raffic interruption caused by the construction also greatly reduce the economic benefits.In view of the shortcomings of traditional paving materials such as easy cracking and poor toughness,this paper aims to achieve low shrinkage and high toughness of bridge deck paving,and relies on the actual project of steel box girder bridge in Qinhuangdao to study the preparation method and performance of C80 mixed fiber concrete suitable for bridge deck paving.Firstly,the test methods such as crossover design and orthogonal design are used to determine the optimal matrix mix ratio of C80.Through the test methods such as the fluidity of cement mortar,the feasibility of replacing silica ash with ultrafine fly ash as a cementitious material was verified,and the dosage range of cementitious material was selected to determine the coefficient-level and evaluation index of the orthogonal test.Taking the ultrafine fly ash content,water-to-adhesive ratio,sand-glue ratio and stone mass fraction as the investigation factors,and the slump,extension,compressive strength and flexural strength as the performance evaluation index,the optimal matrix concrete mix ratio was determined through the verification test,which was 50% cement,25% ultrafine fly ash,25% S95 slag,0.22 water-adhesive ratio,0.1 sand-to-rubber ratio and 0.5 stone mass fraction.Secondly,mixed fiber is used to optimize the matrix concrete.Steel fiber and polypropylene fiber were selected to prepare hybrid fiber concrete.Through testing the slump,compressive strength,bending toughness and shrinkage performance of hybrid fiber concrete,the influence of different volume and dosage of steel fiber and polypropylene fiber on concrete performance was analyzed,and the optimal hybrid fiber ratio was proposed.Steel fiber volume content is 0.75%,polypropylene fiber 0.25%.Finally,the cost performance of bridge deck pavement material is analyzed.The mechanical properties,durability and material cost of C50 polypropylene fiber concrete,hybrid fiber concrete and UHPC were compared on the basis of bridge test section pavement engineering.Within the acceptable cost range,the mechanical properties and durability of hybrid fiber concrete are significantly improved compared with C50 polypropylene fiber concrete.The fiber concrete configuration in this paper can meet the engineering application requirements,and the material cost is only 26.5% of UHPC.It is verified that the hybrid fiber concrete prepared in this paper has higher cost performance and is more conducive to popularization.