| Rapid development of China's high-speed railway construction,the railway engineering projects of the pavement plate and cable slot cover most of the use of reinforced concrete or steel fiber reactive powder concrete cover plate.However,the cover plates of these two materials are both self-important,with low folding strength,corrosion of steel bars,brittle fracture and serious loss of edge Angle.Ultra Hihg Toughness Cementitious Composites can solve the shortness of brittle and cracking of the above two materials by its high performance.In order to solve the current problems of the pavement plate,this paper carried out the PVA fiber with high strength and high toughness of cement matrix composite pavement plate of research and development work,mainly to complete the research contents and results are as follows:Through the control variable experiment,the effects of PVA fiber,fly ash,kaolinite and hydrogel on the strength of composite materials were investigated,The Suggestions of high strength and high toughness cement-based composites are summarized.The combined ratio of 28 d can reach about 90 MPa,and the folding strength can reach up to 18 MPa,which can meet the actual demand of railway pavement cover.To study the microstructure of composite materials,composite materials is analyzed the PVA fiber micro failure mode and the pore distribution of the material,and the micro mechanical properties of the materials with high strength and high toughness.The experimental study on the fiber dispersion,consistency,condensation time,gas content and other physical properties of the new composite materials,come to these conclusions:a)The dispersion of the fibers was obtained by dispersing the dispersant and the mixing process for the fiber dispersion,and the ratio of the water glue was greater than 0.16,and the fiber content was not higher than 2.0%;b)The PVA fiber content is not more than 2%,and the water glue ratio is between 0.16 and 0.24,the composite material has good working performance;c)The incorporation of PVA fiber briefly delayed the initial coagulation time of the composite material,which had little effect on the final coagulation time;d)The production work of composite pavement cover plate is good,and the relevant experience of actual production of cover plate is also obtained.By contrast test,studied the durability of high strength and high strength cement matrix composites,comes to these conclusions:a)The capillary water absorption of composite material is 30% lower than that of cement mortar,and the antifreeze level is higher than F300;b)The composite material has strong resistance to infiltration,and its permeability increases with the increase of age;c)After the age of 28 d,the anti-carbonization performanceof composites was stronger than that of ordinary C40 concrete;d)The antichloride ion performance of composite materials is obviously higher than that of ordinary C40 concrete.The effects of cover width,rib width,rib height and reinforcement type on mechanical properties and deformation of cover plate were discussed by static analysis.Comparison of the six kinds of structure optimization design of cost-effective,obtained the influence law of various factors,and puts forward Suggestions on the best value,namely the plan 6: cover plate and stainless steel wire mesh,flat structure is 600 mm×444 mm×25 mm,rib 10 mm,rib width 40 mm high. |
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