Study On The Material Properties Of Steel Fiber Reinforced Polymer Modified Concrete Using In Special Pavement

In the special pavement project,because of using the particularity of environment and stress,it’s put forward more strict requirements on the mechanical properties and durability of pavement materials.The polymer modified concrete has the good ability of deformation,seepage resistance,wearing resistance to sliding,low shrinkage and steel fiber reinforced concrete has the good properties oftensile,impact resistance,fatigue resistance.The mixed steel-fiber polymer modified concrete keep their merits with the thought of composite material designing.Using the fracture mechanics theory and microstructure analysis of concrete to research the reinforcing mechanism of steel fiber polymer modified cement concrete.At first,based on the fracture mechanics,and through the crack tip closure force model and the energy balance theory these two sides to explain the effects of steel fiber which is decreasing crack propagation force or improving fracture toughness.Then via microscopic observation to find that the polymer can improve the compactness of concrete.At the same time,the film is formed on the surface of steel fiber and aggregate,it’s acts as a ’bridge’.Thereby,it enhances the property of weak interfacial transition zone.Finally,polymer emulsion can be used as curing agent and also can decrease water.Many types of performances andmechanisms are studied in the condition that different fibers are mixed into concrete.Also concrete,steel fiber concrete and polymer modified concretewerecomparedwith controls.The performanceincludes: workability of fresh recycle concrete,dryingshrinkage,the basic mechanical properties of compressive strength,bending,fracture toughness,fracture energy,impact resistanceand durability of high temperature resistance,resistance to high temperature and water,sulfate resistance,frost resistance.In the aspectof compressive property,the polymer results in a slight decrease in the compressive strength of concrete.Therefore,the compressive strengthofsteelfiber polymer modified cement concrete is not obviously enhanced.However,the compressive strength of 7d can reach about 80% of 28 d,which accelerates the development of compressive strength.In the aspect of bending resistance,both the polymer and the reasonable amount of steel fiber can significantly improve the flexural tensile strength of the concrete,the increase inmore than 30% and can greatly increase the ultimate tensile strain,increased from 84.87% to 144.08%.In the aspect of shock resistance,the shock resistance of concrete cracking and shock resistance damage these two aspects are greatly improved under the double effects of polymer and steel fiber.In the aspect of fracture mechanics,polymer and steel fiber are have significant influence on crack resistance,in which the fracture toughness increases by 13.31% to 67.93%,and the fracture energy increases by 15.84% to 228.78%.The shrinkage rate of materials has a substantial decrease by the double effects of polymer and steel fiber,and in each age shrinkage rate than plain concrete is reduced by 30% to 40%.Under different curing conditions,the flexural strength of steel fiber polymer modified cement concrete at different ages has 60℃ curing of curing>regular curing>60℃+water conservation regularity,it shows that the material has good heat resistance,but the high temperature plus the water environment has adverse impacts on the strength of materials.The flexural strength or mass loss rate of normal steel fiber concrete is 2 to 3 times higher than the data of the steel fiber polymer concrete after freeze-thaw cycles and sulfate attack,it is proved that the steel fiber polymer concrete has excellent frost resistance and sulfate resistance.