Preparation And Performance Of Friction Course Materials For Function Of Ice-snow Melting And Self-healing

The maintenance,snow melting,ice melting and self-healing has become the key research object of road materials nowadays.However,the current pavement materials tend to focus on solving a single problem,and the cost of functional pavement materials is often high.Various factors restrict the application and development of such functional pavement materials.In this paper,AC-5 and SMA-5 asphalt mixtures are used as functional friction course materials,and steel fibers and slag are added to modify them to obtain the research direction of functional wear layer materials.The pavement performance,thermal performance,snow-melting and ice-melting performance and self-healing performance of the steel slag were studied.Meanwhile,the effective heating components of electromagnetic induction heating of steel slag were analyzed theoretically.There are the following conclusions:The gradation design of functional friction course materials and the optimization of asphalt-aggregate ratio have been completed in this study.With the increase of steel fiber content in asphalt mixture,the void volume and void in mineral aggregate both show an upward trend,the addition of steel slag can reduce the void volume and void in mineral aggregate.According to the standard,the suggested steel fiber content for AC-5 and SMA-5 asphalt mixture are 1%and 2%,respectively.All the prepared materials have adequate Marshall stability,flow value and moisture resistance.The skid resistance of SMA-5 asphalt mixture is better than AC-5 asphalt mixture.The interface shear resistance of SMA-5 asphalt mixture is lower than that of AC-5asphalt mixture.The addition of steel fiber can improve the fracture strength,fracture energy and fatigue performance of SMA-5 asphalt mixture.Excessive steel fiber content will reduce the fracture strength,fracture energy and fatigue performance of AC-5 asphalt mixture,while the addition of steel slag will have a negative impact on the crack resistance of friction course materials.The thermal constants of AC-5 and SMA-5 asphalt mixtures are affected by volumetric performance,steel fiber content and aggregate type.Both steel fiber and steel slag have a positive effect on the temperature-rising performance of asphalt mixtures.The highest temperature increasing rate is 1.36℃/s.The effective heating depth of ultra-thin abrasive layer materials is 20 to 28 mm.The snow melting and ice melting performance of the material is related to the content of steel fiber and steel slag,and the heating contribution of steel slag can be shown after a long time of heating.The self-healing performance of asphalt mixture is positively correlated with the content of steel fiber.The addition of steel slag will improve the corresponding self-healing performance,and the healing performance is also correlated with the heating time.The healing performance of SMA-5 asphalt mixture is 20%to 45%of corresponding AC-5 asphalt mixture.The healing rate of the material with 3%steel fiber and 120s heating time decreased from 50%to 80%with the increase of healing times to about 15%to 45%.With the increase of the size of steel slag particles,the heating performance of steel slag decreases.The content of iron is also an important factor affecting the efficiency of electromagnetic induction heating of steel slag.Iron and Fe₃O₄ in steel slag are effective heating components.The heating efficiency of iron is less than that of Fe₃O₄ at micron size.Iron mainly depends on eddy current loss.The main heating mechanism of Fe₃O₄ is hysteresis loss and residual loss.The material proposed in this study has qualified road performance,excellent thermal performance,high efficiency of snow melting and ice melting performance and considerable self-healing performance.This material will not damage or rebuild the original pavement,but can be paved on the existing pavement to achieve maintenance,snow melting,ice melting and self-healing functions.It has certain economy and practicability.