The Research On Under-sealed Layer As Transition Pavement During The Winter

The functionality is different when under-sealed layer as the transition pavement during the winter with it is used as a functional layer.The existing design method is not perfect, this paper focuses on the performance of synchronous surface dressing and asphalt sand seal layer during the transition.It provide a theoretical basis for the under-sealed layer as the transition pavement.It will help to promote the technology of under-sealed layer as the transition pavement.This paper focuses on two aspects, it involved with the regular performance and transition pavement performance.The analysis include four aspects,it involved with asphalt type, the amount of material, grading design and porosity.The regular performance of under-sealed layer include interlayer cohesiveness performance, and the winter transition pavement performance include anti-wear properties and frost resistance.The quality of under-sealed layer not only depends on design factors, but also construction factors have an important influence on their quality.This article relies on entitative engineering, which put forward the key construction technologies of under-sealed layer according to the construction inspection.The interlayer cohesiveness performance of synchronous surface dressing uses skew shearing experiment, analysis of how different test temperature impact on its performance. In addition, analysis of how the amount of asphalt, aggregate size, spreading rate of aggregate impact on its performance.It provides a basis for optimization design of synchronous surface dressing.The results showed that the interlayer bonding capacity increases with aggregate size decreases with the increased use of asphalt then decreases.The study of the bonding properties about asphalt sand seal layer, analysis of the influence of gradation designed and asphalt content for performance.It provides a theoretical basis for aggregate gradation designed and reasonable asphalt content.The results show that aggregate gradation close to being the best S-type shear strength, the interlayer adhesion can be improved when it increase the CA value and reduce FAc aggregate value and the thickness ratio.The study of the anti-grind capability about under-sealed layer adopts two kinds of evaluation method, it includes grind type and impact type.The grind type in accordance with sweep test principle, and wet wheel abrasion test about slurry mixture(T0752-2011) has been improved in order to analyze how the material composition impact on performance. Impact type in accordance with vialit test principle, and asphalt and aggregate bond test in low temperature has been improved in order to analysis of how the asphalt content and the aggregate size impact on synchronous surface dressing.It propose that the gravel under seal coat asphalt dosage should be increased to reduce the aggregate size.The evaluation of the anti-frost capability about under-sealed layer, synchronous surface dressing adopts impact test after freezing and thawing. The asphalt sand seal layer uses low-temperature bend test after freezing and thawing. The test results show that two kinds of under-sealed layer types can meet the performance requirements during winter transition pavement and the tar sands seal layer porosity of 4%, the highest frost resistance of asphalt mixture.The research results discusses the seal layer technology design standards and their applicability. It included the amount of asphalt, aggregate size, aggregate spreading rate, grading design, porosity and other factors. This paper presents the recommended values of the parameters, according to project actual weather and traffic conditions can be adjusted.