Test Study On Anti-frozen And Shrinkage Properties Of Stable Granular Base Course Materials In Seasonally Frozen Area

Lime-fly ash stabilized aggregate and cement-stabilized gravel are two semi-rigid base course materials in common use. And they are universally applied in high type highway because of their high strength and good stability and so on. But in recent twenty years, we find out the deficiencies of semi-rigid base course as follows:1.The freeze and thaw destroy during construction and working timeAfter the semi-rigid base course conduction finished, the surface is uncovered during the whole winter, a few freeze-thaw cycles later, the surface is soften and loses strength. And we can't construct on the surface next year. So we must clear away the whole base course and relay. It not only wastes the project fund but also affect the project time.The water content in the semi-rigid base course working circumstance during working time is quite great. After a few freeze-thaw cycles, the base course loses board strength and results in the capacity declining and the pavement destroying. It is also hard to repair and it blocks the travel, wastes fund.2. be easy to crackThe semi-rigid base course material is brittleness. Its drying shrinkage and temperature shrinkage coefficient is big, so it often brings out typical drying shrinkage and temperature shrinkage crack in the project.3. the poor anti-fatigue performanceThere is experience to indicate in domestic that the repeat load times Ne is range from 104 to 105 when the flexural tensile stress level is 0.6MPa.Aim at the deficiency of semi-rigid base course material, this article takes the frost resistance and temperature shrinkage performance of semi-rigid base course in seasonal frost region as project background. Through reading a lot of literature, based on summing-up the former studies on the frost resistance andtemperature shrinkage performance of semi-rigid base course, applied test to systemically study on raw material,mixture ratio design,frost resistance testing methods,boosting up frost resistance method in base course and so on. Provide some usable parameters of semi-rigid base course material in seasonal region.The main studying contents in this article conclude:1. the quality request of the raw material which semi-rigid base course material uses;2. the composing structure and ratio design method of semi-rigid base course material;3. study on the frost resistance testing method and frost resistance index of semi-rigid base course material;4.the impact of semi-rigid base course material ratio and grade on the frost resistance and temperature shrinkage performance of mixture;5. study on the lowest frost resistance strength request of semi-rigid base course material.The study indicates:1.The raw material index has great impact on the performance of semi-rigid base course material; some indexes such as the calcium and magnesium content of lime,the fineness of fly ash,the mud content of aggregate,the quality of cement,the grade of aggregate and so on have impact on lime-fly ash stabilized aggregate and cement-stabilized gravel. By test studying and investigating on construction site, we bring forward some technical index requests of raw material and it has certain reference effect on further applying of semi-rigid base course;2. To analyze the structure theory and choiceness characteristic of interlocking dense type lime-fly ash stabilized aggregate;3. By test studying and trial road observation, we bring forward the frost resistance testing method and index request of semi-rigid base course material;4. By studying, we analyze the shrinkage performance impact factors of semi-rigid base course material, and bring forward the grade and ratio of semi-rigid material which has better anti-shrinkage performance.In conclusions, by interior testing,trial road laying and summing up the former researching fruit, we have general knowledge of the frost resistance and temperature shrinkage performance of semi-rigid base course material in seasonal frost region. We believe it would provide technical support for long-time semi-rigid base course material in seasonal frost region.