Research On Evaluation Indexes Of Bio Solvent Based Cold Patching Asphalt Mixture

With the advantages in construction process,storage,construction time and environmental protection,solvent cold patching asphalt mixture has been widely used in pothole repair recently,which has added momentum to the development of road maintenance technology.However,due to the limited time of cold patching asphalt mixture in China,there lacks sufficient understanding of it.And there is still a lack of scientific and reasonable evaluation standards for cold patching asphalt mixture,at the same time evaluation indexes are difficult to make an objective evaluation to its technical performances.As a result,cold patching asphalt mixture lacks production guidance and varies in quality.In order to make a more scientific evaluation of the solvent cold patching asphalt mixture,the performance evaluation methods and indexes of its were studied by using the self-developed bio solvent based cold patching asphalt mixture as the test material.Firstly,the design of cold patching asphalt and cold patching asphalt mixture for follow-up research was carried out by analyzing the factors that affect the performances of cold patching asphalt mixture.Brookfield viscosity at 60 ℃ was considered the critical index to select cold patching asphalt,and proportion of various ingredients was suggested by the formula design and Brookfield viscosity test.At the same time,based on the design experiences of cold patching asphalt mixture at home and abroad and its own characteristics,it was suggested that cold patching asphalt mixture should be designed with the skeleton type gradation.Three gradations with nominal maximum particle size of 13.2mm(CPAM-13)were designed by using 4.75 mm and 0.6mm as the key sieves.And the optimum asphalt content was estimated separately,which provided a reference for the preparation of cold patching asphalt mixture.Secondly,based on the combination of independent design tests and improvement of existing tests,the evaluation methods and evaluation indexes of cold patching asphalt mixture such as workability,cohesion,strength,adhesion and water stability were studied by using CPAM-13 cold patching asphalt mixture as the test materials.It was proposed that the workability,cohesion,strength,adhesion and water stability of cold patching asphalt mixture should be characterized by mixing appearance and binder drainage loss,damage rate,Marshall stability,coating ratio and Marshall residual stability.Technical requirements for each evaluation index were put forward according to the test results,and an accelerated aging maintenance method for forming cold patching asphalt mixture specimens was proposed.Thirdly,with the CPAM-10 cold patching asphalt mixture,the rationality of the proposed evaluation methods and evaluation indexes was verified.The application test and cost analysis were carried out to verify the performances of CPAM-13 and CPAM-10 cold patching asphalt mixtures.The results showed that the evaluation methods and indexes of cold patching asphalt mixture had proposed above were relatively reasonable,and the self-designed cold patching asphalt mixtures had both performance and economic advantages.Finally,based on the results of field tests and laboratory tests,this paper put forward requirements on raw material performance,gradation design and construction technology,and the construction guideline of solvent cold patching asphalt mixture was formed.