Research On Application Technology Of Thin Overlay With LASTIKA Asphalt Concrete

In our country, considerable parts of Portland Cement Concrete (PCC) pavement and Asphalt Concrete (AC) pavement that have been built in recent years, still have maintained integrity structures, but have had superficial functional distresses such as reveal of aggregate, spalling, skidding, bad comfortableness and so on after several years'using. For those parts of integrity structures, in order to decrease the influence of altitude and save resource, we only need to recover the superficial function for them, and it is a better method to apply thin asphalt overlay. Therefore, with the combination of the project of"Test study of thin asphalt overlay on existing cement concrete pavement"of G321 highway in Zhaoqing City of Guandong Province, this paper conducted the research on application technologies of LASTIKA thin asphalt overlay in existing cement concrete pavement rehabilitation.Based on the analyses of aggregate gradation theories and service performances of asphalt concrete, this paper has studied the LASTIKA thin asphalt concrete with methods of uniform design, step-by-step packing experiment of coarse minerals, orthogonal test optimization design, indoor mixture tests and trial road studies and etc. A range of gradation and content of asphalt and the key techniques of construction for LASTIKA have been put forward that are suitable for our country. All these provide references for the construction of thin overlay on existing cement concrete pavements in our country.LASTIKA thin asphalt overlay is a kind of hot asphalt mixture overlay technology with Superflex modified asphalt, of which the maximum nominal size of aggregate is 9.5mm. Firstly, by the uniform design, the paper studied the influence on voids in coarse mineral aggregate that caused by the three kinds of coarse mineral aggregate: 2.36⁴.75mm, 4.75⁹.5mm and 9.5¹3.2mm. The results show that there are in turn as 2.36⁴.75mm>9.5¹3.2mm>4.75⁹.5mm in terms of influence degree on volume of coarse mineral aggregate. Secondly, the paper has studied proper composition of coarse mineral aggregate with the step-by-step packing experiment, and a reasonable range of gradation composition obtained. Thirdly, the orthogonal test was used to optimize LASTIKA gradation. 5 main factors, the passing rate of 9.5mm, 4.75mm, 2.36mm and 0.075mm and the asphalt-aggregate ratio, and 4 levels were selected, thereby, the orthogonal array L₁₆(4⁵) was selected to arrange Marshall experiments. With the methods of range analysis and variance analysis, the paper analyzed the effect degree and law of Marshall indexes caused by all kinds of factors and levels. The results indicate that passing rate of 2.36mm is the most important influence factor to Marshall indexes as flow value, percent air viods in asphalt mixture and VMA. At the same time, a gradation range and asphalt content of Superflex modified asphalt for LASTIKA asphalt mixture have been obtained, and the correlative formulas between Marshall indexes and remarkable factors were established through analyzing orthogonal experiment results with SPSS statistical software.To check the construction technologies and service performances of LASTIKA asphalt mixture, a trial road of 550m has been paved in G321 highway in Zhaoqing City of Guangdong Province. After a year's using, it has had excellent service performances in fact, this illustrates that the LASTIKA asphalt mixture has good service performances.Therefore, the researches on LASTIKA thin asphalt overlay can offer scientific reference for its application and promotion in our country.