电位滴定法在沥青研究中的应用及展望

Application and Prospect of Potentiometric Titration in Asphalt Research

沥青的组成影响沥青路面的性能。环境和荷载使沥青组分的含量和结构发生变化,导致沥青老化、变硬变脆且粘结性降低,从而降低沥青路面的使用寿命。沥青老化分析技术的发展对研究沥青材料的老化、沥青的改性和老化沥青的再生具有重要意义。当前,应用广泛的傅里叶红外光谱法、凝胶渗透色谱法、原子力显微镜法及荧光显微镜法等在沥青的老化研究中均存在一定局限性,因此,发展一种新的研究方法至关重要。电位滴定法利用已知物质的量浓度的滴定剂对待测溶液中未知浓度的物质进行滴定,溶液中离子浓度变化程度的不同导致指示电极电位显示不同的电势。滴定终点前后,待测物质浓度发生明显改变,电位发生突跃,可根据电位突变时滴定剂的消耗量计算待测物质含量。对于给定的化学官能团,电极电位的变化是唯一的,并且与其浓度成比例。在沥青的检测中,该方法测试结果不受温度、沥青黑色背景、液体接界电位等因素的干扰,因此测试结果具有较高的准确性,适用于沥青组分研究。本文综合国内外研究成果,从监控沥青的老化过程及指导老化沥青的再生角度,综述了电位滴定法在沥青酸碱组分检测与分类中的应用、沥青组分与性能的关系、含水量和硫含量以及苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)改性沥青中SBS含量检测方面的研究进展及其它电化学方法在沥青老化前后的物质检测中的研究现状。通过电位滴定法将沥青老化前后组分的变化与沥青的性能及老化沥青再生机理研究相结合,为沥青路面的耐久性研究提供科学依据。

The composition of bitumen affects the performance of asphalt pavement.Environment and load cause the content and structure of asphalt components to change,which lead to the aging of asphalt,make it hard and brittle,and reduce the cohesiveness and the service life of asphalt pavement.The development of asphalt aging analysis technology is of great significance for the aging of asphalt materials,modification of asphalt and regeneration of aged asphalt.At present,fourier transform infrared spectroscopy,gel permeation chromatography,atomic force microscopy and fluorescence microscopy are widely used in asphalt aging research.However,they all have certain limitations,so it is important to develop a new research method.Potentiometric titration uses the titrant with known concentration to titrate the substances to be measured.The difference of ion concentration in the solution leads to different potential of indicator electrode potential.Before and after the end point of titration,the concentration of the substance to be measured changes significantly,which leads to a sudden potential jump.The content of the substance to be measured is calculated according to the consumption of titrant at the end point of titration.For a given chemical functional group,the change of electrode potential is unique and proportional to its concentration.Potentiometric titration is not affected by temperature,dark background,liquid junction potential and other factors of the sample to be tested.Therefore,potentiometric titration has high accuracy and is suitable for asphalt component research.In this paper,the applications of potentiometric titration in the detection and classification of acid-base components of asphalt,the study on the relationship between asphalt components and properties,and research progress in detection of moisture content,sulfur content,and the SBS content of styrene-butadiene-styrene block copolymer(SBS)modified asphalt are summarized from the perspective of monitoring the aging process of asphalt and guiding the regene-ration of aged asphalt.By potentiometric titration,the change of asphalt components before and after aging is combined with the study of asphalt properties and regeneration mechanism of aging asphalt,which provides a scientific basis for the design of durable asphalt pavement.