Key Technology Research For Asphalt Pavement Ultra-thin Overlay

Express way constructions are gaining momentum rapidly in recent years in China, which meanwhile gave rise to a specific phenomenon that ignoring quality for the purpose of achieving quantity. Many asphalt pavements generated road lots of disease harm long before arriving at designed life expectancy; those problems have bad effects on vehicles driving on. Scientific and reasonable preventive maintenance, not only could effectively enhance the pavement whole service level, but also postpone big and medium restorations, and make fully use of maintenance funds to prolong the road life expectancy. The major method used to restore pavement function in express ways and arterial road in most places is surface construction, but technologically mainly adopt AC as overlay materials. The essay research brings out a SMA asphalt mixture which has nominal maximum aggregate size of 7.1mm. This STOC mixture is not mentioned in China new code. This kind of micro-size particles mixture would greatly decrease road overlay thickness; it is an ultra-thin overlay materials which would extensively applied in preventive maintenance. Through researching, the essay concludes that STOC could design discontinuous skeleton dense texture, and have the properties of high-temperature stability and low temperature crack resistance.The research took Gan Su province asphalt pavements maintenance ultra-thin overlay key technology as research facts support; fully considers the local nature, communication conditions, to discuss the 7.1mm nominal maximum aggregate size SMA mixture. The essay discussed following problems:aggregates, aggregate gradation, mixture design methods, ultra-thin overlay, interlayer bonding, shear behavior, and road indexes. I firstly introduce traditional foreign and domestic reference about micro-size particles SMA structure properties. Secondly the essay brings out gradation range of STOC mixture and that STOC asphalt mixture's coarse and fine gradation dividing point is 2.36mm screen aperture, meanwhile define this key screen aperture passing rate range is between 20% and 35%. The research is using traditional Marshall design methods so as to find the optimal asphalt-aggregate ration, then introduce into mechanical index(SCB) SCB, which effectively avoid disconnection between materials and structure design. Through indoor rutting experiment, compound specimen rutting experiment, manual sand spreading method of measuring structure deepness, and seepage test, the research aims to test STOC pavement performance.I looked up massive references, concluded STOC mixture applicability and that it could be an important method as preventive maintenance measures. Finally, the essay analyzes ultra-thin overlay shear stress through BISAR software, comes to the conclusion:when interlayer is continuously contact, the maximum shear stress is less. Through high temperature shear test, pick LJT as the optimal interlayer bonding material. LJT's comprehensive performance is better than epoxy asphalt and SBS modified asphalt and its tensile strength was testified by pull-out test.