Study On Road Performance Of Steel Fiber-reinforced Asphalt Concrete

In the thesis, the influence of steel fiber on the road performance and composition of asphalt concrete is studied through kinds of tests such as Marshall, rutting, bending at low temperature, freeze-thaw splitting.The optimal asphalt aggregate rate of asphalt concrete AC-13and3kinds of different content of steel fiber asphalt concrete were determined through Marshall test. The results show that: with the growth of steel fiber content, the increased amount of asphalt is not the same proportion; with the increasing of steel fiber content, the growth amplitude of the optimal asphalt aggregate rate also showed an increasing trend.High temperature stability of steel fiber asphalt concrete is analyzed through rutting test. The results indicate that steel fiber can improve high temperature stability of asphalt concrete. There is no a direct linear relationship between steel fiber content and high temperature stability of asphalt concrete. Improvement effect of steel fiber on the high temperature stability of asphalt concrete is also affected by other factors, where the asphalt content is the most important factor. The content of steel fiber must match the increment of asphalt; otherwise, the expected enhancement effect can not be reached. According to the test results, dynamic stability prediction model considering the content of steel fiber and the increment of asphalt is established.Through bending test, the influence of steel fiber on low temperature crack resistance of asphalt concrete is researched. In the temperature range from-40℃to＋10℃, with the descent of temperature, flexural strength of asphalt concrete almost decreased linearly, the addition of steel fiber does not change the nature of asphalt concrete that flexural strength reduces with the falling of temperature, but it changes the value of bending strength. Steel fiber can improve the flexural strength of asphalt concrete, and with the increasing of steel fiber addition, flexural strength also showed a rising trend. With the decreasing of temperature, the strain of steel fiber asphalt concrete with different steel fiber content decreases, but at any temperature, the deformation resistance increase gradually with the increasing of steel fiber content. Steel fiber also affects the stiffness modulus. At a certain temperature, with the improving of steel fiber content, stiffness modulus decreased clearly.Through freeze-thaw splitting test, the effect of steel fiber on water stability of asphalt concrete is studied. The test results show that under the same volume features (such as porosity), steel fiber can improve the freeze thaw splitting strength and resistance to water damage property of asphalt concrete effectively. The freeze thaw splitting strength ratio of asphalt concrete with1%steel fiber content is improved by5.2%.