Application Research Of Cold Recycling Technology Using Foamed Asphalt

Depending on data investigation, laboratory test, theoretics analysis and experience summing-up, this thesis discusses asphalt foaming characteristic and evaluation method of cold recycling technique for foamed asphalt, mixture performance and its correlative factors, material characteristic and gradation, mix design and construction experience. It can improve the theory of this technique and guide material design and construction application in the future.By asphalt foaming test, asphalt foaming characteristic and its effect factors are studied, what's more, the relationship between asphalt foaming effect and the foamed asphalt mixture performance is discussed. The test shows that asphalt origin, foaming water content and foaming water temperature can markedly affect foaming results, however, asphalt temperature can not. When foaming water content is increasing, the changing rules of foaming index will vary. It is also found that there is little relationship between asphalt foaming effect and corresponding mixture performance. Then the limitation of "the optimum foaming condition" is analyzed and it is advised that it should be instead of "proper foaming condition" in construction application guidance.The material characteristic, gradation design principle and the criterion of mineral powder passing percentage of foamed asphalt mixture are all discussed. After describing aggregate appearance, the classifying criterion and gradation effect factors of RAP (Recycled asphalt pavement) are analyzed. Based on laboratory data, mixture strength forming mechanism and construction experience, it is considered that RAP gradation should be chosen to guide construction and gradation design course. Because passing percentage of mineral powder is always lower in construction both in and abroad, laboratory test is taken. At last, it is found that fine performance mixture can be gained even if passing percentage of mineral powder is below 3%. Therefore, it is advised that the criterion of passing percentage of mineral powder should be a bit lower. This thesis also optimizes the mix design process of cold recycled for foamed asphalt. By orthogonal test, simple and unilateralism design course in existence is improved so that it can more comprehensively consider interactional primary design factors. At last all the primary design factors can be deduced simultaneity, including the optimum asphalt content, mixing water content and design gradation, etc.