Study On The Foamed Bitumen Used In Cold In-Place Recycling Of Asphalt Pavement

This paper firstly gives a presentation on the development and application of the asphalt pavement recycling technology, analyze the feasibility and essentiality of the asphalt pavement recycling technology. Based on that, this paper particularly introduces the recycling principle, recycling type, construction machine, application object and application manner of asphalt pavement in-place recycling technology. Meanwhile, makes a contrast with three ways of in-place cold recycling construction; expatiates the construction techniques characteristics and advertent questions of the in-place cold recycling technology.Secondly, by carrying out the foaming test of four kinds of popular bitumen(PanJin AH-70, ZhongHai AH-70, ZhongHai AH-90, Shell AH-70), the paper analyzes the variational relation between the evaluation parameters of foaming characteristics (expansion ratio and half-life) and the factors influencing foaming characteristics (quantity of foaming water and foaming temperature), and finds out the best foaming conditions for the four types of bitumen. The result of foaming test is validated by foaming exponential. On the basic of the result, this paper brings forward that the expansion ratio and half life can be regarded as the evaluation pavements of the best foaming condition, and the foaming exponential is regarded as the checkout parameter of test's result.Finally, development and application of foamed bitumen is introduced. The foamed bitumen in-place cold recycling technology is expatiated, including the characteristic of material, the design of pavement and the capability of foamed bitumen mixture. The capability and parameters of some cold recycling machines, such as WR2000, 2200CR, WR2500S, WR4200, are described. Combining with the construction of 320 national highway TongXiang—ChongFu, foamed bitumen in-place cold recycling technology, cement in-place cold recycling technology and plant-mix cold recycling technology of foamed bitumen are introduced. Meanwhile, economic benefit and social benefit of three ways are analyzed and compared. This paper makes a conclusion that the foamed bitumen in-place cold recycling technology is the best way among the three ways.