The Release Of Volatile Organic Compounds In Asphalts And Its Influences On Asphalt Performances

Asphalt has been widely used in road engineering and construction waterproof field and the consumption in China is more than18million tons, ranking second in the world. However, asphalt can produce volatile organic compounds in ambient temperature and pressure in the service process, and high temperature or infrared, ultraviolet may promote the release of VOC, leading to the deterioration of its performances and reducing life expectancy which increased the consumption of resource and energy. Based on the laboratory conditions of VOC emission, VOC generator device was established and effects of VOC emission on the performances under different conditions, focusing in non-high temperature environment, were studied in this paper.First, emission under different environment was studied by the quality change of asphalts. Results shows that quality reduced at high temperature while the situations was complex at the temperature less than70℃; VOC generating device and sampling and analysis were established in this paper, outcomes show that quality loss at high temperature can represent VOC emission capacity, while different conditions take different impacts on the different asphalts at non-high temperature environment.Second, effects of VOC emission under non-high environment conditions on its performances were studied in this paper. Asphalts used in this paper was mainly SK-70、PJ-90and SBS, and conditions included infrared, ultraviolet and vacuum and so on. Quality loss in Vacuum condition is the least, moreover all values including soften, VAI and PI representative for colloidal structure increase with the minimal variation in Vacuum condition; there are some differences between infrared and ultraviolet because of the mechanism to asphalt. After VOC emission from asphalt, elastic components in the asphalt increase and exhibit a more complicated composition changes, the ultimate strain reduced greatly and generalized shear modulus increases.Finally, component change test, DSC and FT-IR test were used to study the microscopic properties of the asphalts before or after VOC emission, mainly focusing on non-high temperature environment conditions. Results show that the total contents of aromatics and saturates reduces after VOC emission and there is the minimal reduction in Vacuum condition. DSC data show that the arrangement of asphalt molecules become larger and neatly, and the compositions may change in the experiment temperature range decrease. Infrared spectrum tells that there is little change in peak position in non-high temperature emission condition, but some change in peak area mainly in the decline of the alkane portion. In high temperature emission condition, alkane absorption peak significantly weakened and the components of aromatics and saturates considerably reduce. The functional group index, C=O and S=O, in non-high temperature emission condition was also studied, results show a decline slightly in Vacuum condition while increase in infrared and ultraviolet conditions, and the variation of C=O is larger.The findings and research ideas in this paper can be used for searching for the mechanism of VOC emission from asphalt, laying a basis and guidance for future research and methods, which also provide the research directions for VOC suppression technique.