Study On Physical And Mechanical Properties Of Cold Recycled For Foamed Aspfalt Mixtures

Depending on data investigation, aboratory test, theoretic analysis and the actual project situateion, this thesis discusses asphalt foaming characteristic, evaluation method of cold recycling technique for foamed asphalt and the factors which have an impact on the asphalt foaming, the influence of the method of laboratory test on the performance of foamed asphalt mixture and mixture design. Through the 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 also discussed. According to the laboratory test, gradation, asphalt content, mixing water content and method of curing are studied to analysis their affect on the properties of the foamed asphalt mixitures. This thesis also optimizes the mixiture design process of cold recycled for foamed asphalt and shear strength is introducted as a validate index of the performance of foamed asphalt mixture.And the influence factors of its shear strength and the shear strength change trends were also studied.Through laboratory test asphalt foaming characteristic is studied and its influential factors are identified by way of analysis of variance.The results show that the influential factors of asphalt foaming is different in terms of different asphalts.The factor which significantly affects CNOOC AH-70# asphalt is foaming water content, while foaming water content, asphalt temperature and their interaction significantly affects Shell AH-70# asphalt's expansion ratio and foaming water content is the influential factor of Sheel 70# asphalt.Physical and mechanical properties are studied according to the laboratory test results, and the influnces of gradation, mixing water content, asphalt content and the method of curing on properties of foamed asphalt were also anlyzed.With the same gradation and asphalt content, the ITS(indirect tensile strength) and TSR(tensile strength ratio) of the mixture of Shell 70# is greater than the mixture with CNOOC 70# asphalt, because the former mixture has the better foaming results in the asphalt foaming test. In terms of the same mixture, the ITS and TSR show a tendency of decreasement after previous increasement with the increase of asphalt content, which is concerned with the relative contrast of structural asphalt and free asphalt.Void ratio is an important factor, as water stability of foamed asphalt mixture will change significantly when.its void ratio surpasses 8%, and at this moment the mixture bears the most sereve water damage.That the mixture is infiltrated or not in the compaction not only affects the mixing water content , but also has a furt -her impact on the mixture's ITS.The test results show that the mixtures without infiltration have higher ITS than the infiltrated mixtures when the asphalt content is low(below 1.8%), while the infiltrated mixtures have higher ITS than the mixtures without infiltration when the asphalt content is high(beyond 1.8%).The thesis also optimizes the mix design process of cold recycled for foamed asphalt.That is, the maximum wet ITS is chosen as the standard of asphalt content in the design, and Marshall stability is chosen as validate indicator.In a word, the mix design should consider the combined effects of water stability and high temperature stability.Finally, based on cold in-plant recycling and cold in-place recycling of trial section of Zheji -ang 04 provincal highway, construction technology process, construction organization manage -ment and the method of quality control are concluded, which accumulates experience for the cold recycling of foamed asphalt.From construction process and test results of the trial section, compared with cold in-place technology, cold in-plate technology has higher mechanization, which makes it be easier controlled and be accepted by construction companies.Though cold in-place technology has less processes, manual operation and costruction by lanes lead to poor smoothness, so strengthen construction organization management and construction quality control are keys of guaranteeing the quality of cold in-place recycling construction.