基于衰减全反射红外光谱技术的水在沥青中扩散过程研究

Study on Water Diffusion in Asphalt Based on FTIR-ATR

采用衰减全反射傅里叶红外光谱技术,以羟基伸缩振动峰面积为量化指标,研究了水在沥青中的扩散过程,并探讨了温度、压力和沥青老化等因素对水在沥青中扩散系数的影响.结果表明:扩散入沥青中的水的总量与羟基伸缩振动峰面积之间存在对应关系;水在沥青中的扩散过程可分为2个阶段,第一阶段以吸收自由水为主,扩散系数较高,第二阶段以水分子与沥青分子或极性基团的结合为主,扩散系数较低;温度和压力的提高均会增强水在沥青中的扩散能力;老化会降低沥青对水扩散的抵抗能力,使水在沥青中扩散的第一阶段显著加快.

The peak area of hydroxyl stretching vibration was quantified to study the diffusion process of water in asphalt by Fourier transform infrared-attenuated total reflectance spectroscopy(FTIR-ATR),and the influences of temperature,pressure and asphalt aging were also investigated.The results show that there is a correspondence between the area of the OH stretching and the water content diffusing into asphalt.Moreover,the diffusion process can be divided into two phases,in the first phase the priority is given to absorbing free water with a higher diffusion coefficient,and in the second phase water molecules and asphalt molecules or polar group are combined,the diffusion coefficient decreases correspondingly.The increase of temperature and pressure enhances the diffusion ability of water in asphalt.Meanwhile,aging can reduce the resistance of asphalt to water diffusion and accelerate the diffusion of water,especially in the first diffusion phase.