Characteristics And Engineering Application Of Self-monitoring Asphalt Concrete

The asphalt concrete has been widely applied in the road and bridge pavement By the end of2012, the highway mileage has reached90000kilometers in china which ranked the second in the world. With the development China’s highway industry, the focus of work has been gradually turned a sample construction into a development pattern which includes build, manage and maintenance. And the pre-maintenance and maintenance has been aroused widely concern. Through the collecting and analyzing the resistance data, the self-monitoring asphalt concrete can be scientific guidance the pre-maintenance and maintenance of asphalt pavement in the early damage which occurred in the pavement structure. In order to avoid the permanent destroys, it’s necessary to take corresponding measure to recover its normal pavement performance. It is of great importance to economic and social benefits that extend service life, reduce maintenance cost, and terrible environment which caused by waste asphalt concrete.l.In this paper, during the design process of self-monitoring asphalt concrete grading, take examples by Superpave volume indicator design method and Bailey parametric method, then designing and proving with the use of Marshall design approach, and preparation the self-monitoring asphalt concrete. The research found that refer to the resistivity of self-monitoring asphalt concrete in the test, the bailey parametric of the AC-20self-monitoring asphalt CA is0.5～0.65, FAc is0.35～0.45, FAf is0.35～0.4; and it also determined the graphite content is3%and the best asphalt dosage is4.8%.There is transfusion phenomenon which exists in the electric conduction phenomenon of self-monitoring asphalt concrete, percolation threshold existence in graphite content, and its conductive mechanism is as a result of conductive particles inside contact effect and transfusion effect combined action2. This paper based on the industrial construction of Caofeidian, Tangshan, paved a self-monitoring asphalt concrete test section, with the help of construction organization equipment, studied the mixing, paving, electrode embedding and compacting of self-monitoring asphalt mixture. The study showed that the addition of graphite is extract from second powder recycle device, and add to the mixing pot. The optimum batch process is hot aggregate dry mixing5seconds, and adds graphite and asphalt at the same time, then mixing35seconds. Paving speed should be controlled in1～3m/min, using non-contact balance beam control paving thickness, identify the paving thickness coefficient is1.2. Electrode embedded needs two steps as follows: lower electrode fixed first, then embedded upper electrode in construction. During compacting, should be used tyre roller pressure first, and then used steel roller and tyre roller alternate pressure within15minutes.3. In this paper, after the self-monitoring asphalt pavement test section construction, chosen four periods which are the early construction stage, summer period, winter period and the spring melt period as study object for one year service. Evaluate its pavement performance through several tests such as volume performance, high temperature stability, water stability, low temperature cracking resistance and fatigue resistance performance. And analyzed the variation of electrical performance under multiple factors and taken the temperature of Caofeidan and geological conditions into consideration. The research found that at the beginning of the construction, with the orderly execution conditions, the self-monitoring asphalt pavement has a good performance. After one year service of summer period, winter period and spring melt period, the pavement performance has been different degree decline. Under multi-factor conditions, its resistance value increased, micro cracks may occur in the internal structure, and in addition, metal electrodes also suffered inordinately corrosion.4. In this paper, on the basis of the self-monitoring asphalt pavement test section, established a maintenance-decision model after data acquisition and processing which include the pavement damage date index DR, the pavement structure capacity index SSI, the pavement track depth index RD and the key pavement resistivity index RI. The study showed the through the test section data collection and analysis, the maintenance-decision model can be timely and effectively make a comprehensive assessment to the asphalt pavement.