Study On Preparation Of Pavement Cover Based On Hybrid Fiber And Basalt Products

SFRPC(steel-fiber Reactive powder concrete)used in railway has serious problems in concrete materials,preparation process and structure,so it is necessary to develop new cover plates.HFFC(Hybrid flexible-fiber concrete)can realize the combination of high strength and high toughness.Basalt material products not only have excellent mechanical properties,but also do not have the problem of rust,so this paper will focus on HFFC production process optimization and mix ratio optimization,supplemented by the use of basalt products for structural optimization,the development of a new type of railway cover plate,the main work is as follows: first,HFFC preliminary mix ratio is designed;Then the special production process matching with HFFC is explored.Furthermore,the mixture ratio of HFFC with high strength and high toughness was obtained through further optimization.Then a new type of cover plate structure is designed by using finite element model analysis.Finally,the bearing capacity and deformation performance of the new cover plate are evaluated.Mainly completed the following research work:(1)Combined with the workability,mechanical strength and deformation indexes,the preliminary mixing ratio was obtained through orthogonal test,and the production scheme was improved by adding dispersant,fiber prewater retention and high strength stirring.Then the optimμm curing scheme of HFFC60℃ high temperature steaming for 3 days was put forward by single factor variable method.Finally,the overall process is evaluated and the new process can effectively improve the stability of HFFC performance;(2)Based on the ultra-fine polymerization theory,the influences of silica fμme fineness,mineral powder activity index,cement variety,water consμmption and quartz sand on compressive resistance,bending strength and ultimate deflection were investigated,and the technical indexes of HFFC matrix raw materials were proposed.The 28 d compressive strength of the strengthened matrix was up to 90 MPa,the bending strength was up to 18 MPa,and the ultimate deformation was up to 0.45%,which preliminarily realized the combination of high strength and high toughness of HFFC;(3)Based on the hybrid fiber theory,the optimal fiber parameters were calculated.The mechanical properties of concrete were characterized by compressive strength and flexural strength,and the deformation properties of concrete were characterized by ultimate deformation.The optimal length-diameter ratio and content of PVA fiber and basalt fiber were obtained by single factor method.The enhancement and toughening effects of each fiber combination were studied by introducing a confounding coefficient.When basalt fiber is 6mm in length,17μm in diameter and volμme content is 0.3%,and PVA fiber is 6mm in length,5μm in diameter and volμme content is 0.55%,the matrix can obtain the best mechanical and deformation performance,28 d compressive strength is up to 100 MPa,bending strength is up to 20 MPa,and the ultimate deflection can be up to 1.1%,further optimizing the high strength and high toughness of HFFC;(4)Based on the developed performance parameters of high strength and high toughness HFFC,the cover structure was designed,and the strength grade of HFFC was determined to be at least C80,and the best thickness of the cover was 35 mm.Besides,the design method of basalt composite reinforcement replacing steel and basalt border and edge was adopted,and three structural schemes were proposed;(5)Based on the test results,the optimal structural scheme of 2 basalt composite bars with a diameter of 6mm and basalt frame was determined.The maximμm bearing capacity was 8.72 KN,the ultimate deflection was 11 mm,and the bearing capacity was maintained for at least 30 seconds in the limit state.After unloading,the secondary load can be up to4.32 KN,which can realize the early warning before the cover plate is broken and the insurance after the break.