Special Hybrid Steel Fiber Polymer Modified Concrete Pavement Material Performance Research

Polymer modified concrete and steel fiber reinforced concrete are two excellent pavement materials,which have many advantages,but there are also shortages.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 of tensile,impact resistance,fatigue resistance.The mixed steel-fiber polymer modified concrete keep their merits with the thought of composite material designing,but overcome the shortages.Mechanism of polymer modification was investigated from the microscopic view using scanning electron microscopy(SEM)and the mechanism of steel fiber resistance cracking was investigated from theoretical view using composite mechanical theory,fiber distance theory and force model of crack tip.The effect of steel fiber on the stress intensity factor of crack tip and maximum tensile stress was investigated from finite element simulation by establishing the finite element model of steel fiber resistance to crack.Many types of performances and mechanisms are studied in the condition that different fibers are mixed into concrete.Also concrete,steel fiber concrete and polymer modified concrete were compared with controls.The performance includes: workability of fresh recycle concrete,drying shrinkage,the basic mechanical properties of compressive strength,bending,fracture toughness,fracture energy,impact resistance and durability of high temperature resistance,resistance to high temperature and water,sulfate resistance,frost resistance.The main conclusions are as follows:The multi-level crack resistance network is made of polymer mesh membrane,the ultra short steel fiber and corrugated steel fibers.Polymer mesh membrane and the ultra short steel fiber prevent or delay the generation and extension of tiny cracks inside the concrete.Corrugated steel fiber prevents the development of the macroscopic fracture.The energy that causes cracks is a large number of consumption in overcoming the multi-level resistance crack in the network.Polymer improves the water retention and the workability of concrete.Incorporation of polymer and fibers has a certain effect on shrinkage of concrete and cracks caused by Shrinkage Stress.When steel fiber volume content is low,generally less than 3%,the steel fiber slightly increase the compressive strength of concrete,and when the steel fiber volume content is higher,generally more than 4%,the compressive strength will decrease slightly.Relatively plain concrete,the steel fiber polymer modified concrete peak force of compressive strength is slightly smaller,but its elastic modulus is smaller,so that the vertical displacement will be larger and the press will do more work when specimen damage.The addition of steel fiber can obviously increase the flexural strength of concrete,with the range of 22% ~ 62%,and corrugated steel fiber played a larger role in the flexural strength than the ultra short ultra fine steel fiber.There will be clear serrated shape for hybrid steel fiber reinforced polymer modified concrete after the peak load of load-deflection curve and the serrated shape describe the process that a corrugated steel fibre is pulled up.The ascent stage describe the process that a corrugated steel fibre is pulled up and the descent stage describe the process that bearing capacity drops after pulled up.Hybrid steel fiber reinforced polymer modified concrete has superior deformation performance and the limit strain is four to six times more than the concrete.Hybrid steel fiber reinforced polymer modified concrete has superior performance on fracture toughness,fracture energy and ductility than steel fiber concrete.The range of fracture toughness is 5.3% ~ 33.8% and the range of fracture energy is 9.8% ~ 107.2%.With steel fiber volume content increase,the initial-crack,fracture impact cycle number and impact energy increase and the destroyed main fracture by one to more.Compared with steel fiber reinforced concrete,mixed steel fiber polymer modified concrete has better anti-high temperature,high temperature and water,anti-sulfate,anti-freezing properties.The flexural strength of 28 days ago on 60℃ is bigger for hybrid steel fiber reinforced polymer modified concrete,with the range of 22% ~ 62%,than normal temperature.The flexural strength of 28 days ago on 60℃ water decrease slightly for hybrid steel fiber reinforced polymer modified concrete than normal temperature.