Application Technology Research Of Natural Gravel Materials In Road

Xinjiang has a very rich sand and gravel material which occupies one-sixth of the national territory area and is sparsely populated. Their road construction characteristics are long line and small traffic volume.If the road structure of"thin layer of asphalt mixture"+"graded gravel road base"is be adopted rather than the traditional semi-rigid structure,it will reduce the project cost and promote the low-grade road development in Xinjiang.The gradational and basic mechanical parameters of natural gravel material are obtained through indoor and outdoor experiment of physic and mechanical properties.Also, the strength, compression performance, bearing capacity, water stability and frozen stability performance of gravel material at different gradational are gained by bearing-plate test and large scale triaxial test.Based on the above conclusions, the relation between the design parameters and pavement performance is got.Through the construction of experimental road in different climate zones, the construction techniques and control index are acquired. The theoretical analysis and laboratory test results are verified and amendmented by the experimental road, which can further improve the design parameters of western natural gravel materials in existing norms.The main results of this study are as follows:1. Natural gravel material is well road material, which is completely feasible to be used as road base material in second-class highway with a lower traffic or below second-class highway asphalt pavement.2. Gravel is typical non-linear material, the resilient modulus changes with the major and minor principle stress. The resilient modulus increased with the increasing major and minor principle stress. At the same time, the more content of gravel, and the higher resilient modulus. The mixture's ability of resist deformation is stronger with the greater density and its bestconten of t gravel is about 70~80%.3. The advised gradations of gravel aggregate are put forward. According to the relationship between n value and the maximum dry density, the relationship between the largest gravel size and the maximum dry density when n value is the same, four different gradation of the curve are recommended.4. Through the construction of the experiment test, the road construction control technologies are gained, and the infiltrate laws of gravel sub base are gained at the same time.5. Through the comprehensive analysis and evaluation to test road opened one year after,it is clear that asphalt pavement with natural gravel base has a good road performance.Research results have some reference value on the road structural design, road construction, maintenance and natural gravel application of western region.