Study On Pavement Performance Of Cement Stabilized Macadam With Emulsified Asphalt And Flexible Fiber

The disease of reflection cracks often occurs in semi-rigid asphalt pavement. To improve the crack resistance of the semi-rigid asphalt pavement, the paper modifies the properties of the cement-stabilized gravel by two materials, namely emulsified bitumen and polypropylene fiber, basing on the anti-cracking enhancement mechanisms of the two mentioned materials.Combining with theoretical analysis and experimental research, the paper first has completed the model selection research about emulsified asphalt and flexible fiber, and we decide to use the slow-cracking rapid solidification cationic emulsified asphalt and 19 mm polypropylene fibers. CTM, CBTM-2, CBTM-3, CBTM-4 and PPCBTM, those five different mix proportions are used by changing the dosage of emulsified asphalt and flexible fiber. Based on a serious of experimental research on mix proportions, we have draw the following conclusions:When adding emulsified asphalt, the compressive strength, splitting strength and bending strength are decreasing.The falling rage of intensity is positively correlated with mixing amount of emulsified asphalt. By analyzing the ratio of compressive strength and splitting strength,we find that whether adding emulsified asphalt and flexible fiber or not, the ratio of compressive strength and splitting strength are sable at 8.4-9.1. Flexible fiber-emulsified asphalt cement stabilized macadam can retain its integrity when destroyed by pressure, and it also still has better ductility and bearing capacity when it works under crack. Emulsified asphalt can increase flexibility of cement stabilized macadam, reducing compressive resilient modulus and bending back elastic modulus, and the falling degree is positively correlated with the mixing amount of emulsified asphalt. Polypropylene fibers can further reduce resilient modulus of emulsified asphalt cement stabilized macadam. Emulsified asphalt can increase the ultimate strain of cement stabilized macadam, and 3% emulsified asphalt can enhance ultimate strain of cement stabilized macadam by 67.5%, which effectively alleviates the problem of cracking due to the large strain in base course. Polypropylene fiber can effectively improve the toughness of emulsified asphalt cement stabilized macadam. After adding polypropylene fibers in it, the toughness index of mixture is also significantly higher than ordinary cement stabilized macadam toughness. Crack propagation need to absorb more energy when toughness is improved, which can slow down the pace of crack expansion in base course. Polypropylene fibers can enhance the critical crack opening displacement, fracture toughness, and fracture energy of emulsified asphalt cement stabilized macadam. Polypropylene fibers can also improve fracture performance of emulsified asphalt and can reduce the temperature-shrinkage index of emulsified asphalt cement stabilized macadam.By the composite mixing of two materials with different properties, the paper modified the properties of cement-stabilized gravel, effectively improving such properties of the gravel as deformation, toughness and anti-shrinkage, which provides a new method for the research of anti-cracking of semi-rigid base course material.