Research On The Key Technology And Application Of Cold In-place Recycling For Highway Pavement

Using cement as stabilized agent, the method which the old base materials is recycled with the in-place recycler is an advanced road maintenance technology. Laboratory tests and application research are developed in order to solve some key technical issues encountered during the engineering practice in this paper.First of all, discussing the influence factors of cold recycled pavement material with cement stabilization by analyzing intensity forming principle of that according to the characteristics of old pavement materials. Analysis and evaluation for the raw material properties of cold recycled mix with cement stabilization show that the content of old asphalt concrete and the gradation of mixture are the main factors on influencing the pavement performance indicators of the cold recycled mix with cement stabilization. Based on the different content and the aging degree of old asphalt concrete, the following rules are found:When the asphalt is not aged seriously, the mix with higher concentration of old asphalt concrete can lower the compressive strength, indirect tensile strength, modulus of resilience and stabilization of recycled material in each curing period and improve temperature sensibility. On the contrary, anti-erosion performance and plastic shrinkage of recycled material are improved appropriately as well. Because of the differences of the mixture gradation, it is shown that after adding coarse aggregates in old semi-rigid base materials, its gradation can be improved, the type of dense skeleton can be formed, overall density is increased, the best moisture content is reduced, and the compressive strength, indirect tensile strength, and compressive modulus of resilience of the mix are increased significantly, besides, its stabilization, anti-erosion performance and plastic shrinkage can also be improved. Then, the application conditions and situations are proposed according to the different composition of recycled materials.According to the former indoor theoretical research and previous engineering experience, combing the characteristics of in-place recycling technology, the design method of cold recycled mix with cement is put forward and the specific sampling methods, analysis of raw materials, grading design and forming method for the old pavement material are emphasize.Through the investigation and survey of cold in-place recycling construction situation and the reference of the rich application experience in China and abroad, the construction technology principle of in-place recycling with cement, the main equipment requirements, the construction process and the quality control method of cold in-place recycling, the quality inspection during process and the acceptance standard of the project quality are proposed.In accordance with the application of the semi-rigid base cold in-place recycled with cement in Jiande Section of the national highway G330and Longquan Section of the province highway S229, the old pavement condition, maintenance plan,construction preparation, construction achievements of the test section, construction effect observation and analysis, economic and social benefits analysis are introduced, and then the basic experience for applying cold in-place recycling technology is summarized.