Abstract:In order to simulate the climatic characteristics of high temperature and high humidity in summer and micro-freeze-thaw in winter in Hangzhou of China, and to take into account factors such as cycle numbers, temperature, oxygen, water and other’s factors, this paper designed “Dry-Wet and Freeze-Thaw” (DW-FT) cycles test in laboratory. Base asphalt and styrene-butadiene-styrene (SBS) - modified asphalt were experimental specimens, basis on the thin film oven (TFOT) -aged of asphalts, the Fourier Transform Infrared spectroscopy (FTIR) and Gel permeation chromatography (GPC) test techniques were used to qualitatively and quantitatively analyze the characteristic functional groups and molecular weight distribution of asphalts before and after the “DW-FT” cycles test in order to study the water aging characteristics of asphalt. The experimental results indicated that, with the increase numbers of “DW-FT” cycle, the oxygen aging characteristic peaks of the carbonyl index changed little under the condition of mild-oxidation (60℃), and of the sulfoxide index increases obviously, the butadiene index of SBS asphalts decreases obviously in infrared spectra analysis; The number-average molecular, weight-average molecular weight,polydispersity and the large molecule size (LMS) content increased gradually with the increase numbers of “DW-FT” cycles in the GPC test. So the sulfoxide index and LMS% could be used to characterize the water aging degree of the asphalts. Both FTIR and GPC test results showed that the effect of the “DW-FT” cycles in water environment can accelerate the aging of asphalts materials, and the SBS modified asphalt had greater water ageing resistance than the base asphalts.