老化对改性沥青宽温度域黏弹特性的影响

Influence of Aging on the Wide-Temperature-Range Viscoelasticity of Modified Asphalt

关键词:  SBS改性沥青  老化  温度扫描试验  线性黏弹特性

Key words:  SBS modified asphalt  aging  temperature sweep test  linear viscoelastic

摘要:

采用红外光谱与凝胶渗透色谱研究改性沥青的老化机理，并依托宽域温度扫描试验，检测沥青材料在20~140 ℃内的线性黏弹特性变化，讨论短期老化与长期老化的影响规律.结果表明：苯乙烯-丁二烯-苯乙烯嵌段共聚物（SBS）改性沥青是典型的两相材料，其老化过程由沥青相氧化硬化与SBS相氧化裂解耦合组成；沥青相老化时吸收氧气发生聚合，相对分子质量逐渐增大，沥青逐渐变硬变弹；SBS相老化时吸氧裂解，相对分子质量逐渐变小，沥青逐渐变软变黏，2种行为同时存在，共同影响改性沥青的黏弹特性；温度较低时，沥青硬化作用占优，老化后相位角下降，模量上升；温度较高时，SBS裂解作用占优，老化后相位角上升，模量不变甚至下降；短期老化中，SBS裂解作用较为明显，长期老化中，沥青硬化作用占据上风.

Abstract:

Infrared spectroscopy and gel permeation chromatography were used to study the mechanism of modified asphalt， and rely on the wide range of temperature scanning test to detect changes in linear viscoelastic characteristics in the range of 20-140 ℃， discussing the short-term aging and long-term aging influence. The results show that the styreneic block copolymers（SBS） modified asphalt is a typical two-phase material whose aging process is composed of asphalt oxidation hardening with SBS phase oxidation. When the asphalt phase is aged， the oxygen is absorbed， the relative molecular mass gradually increased， and the asphalt becomes hard and elastic. When SBS is subjected to oxygen， the relative molecular mass is gradually smaller， and the asphalt gradually becomes soft and viscous. The two behaviors exist simultaneously and affect the viscoelastic characteristics. When the temperature is low， the asphalt phase hardening is predominating， the phase angle of aging is decreased， the modulus rises. When the temperature is high， the SBS degradation dominates， the phase angle increases， and the modulus may even decline. In short-term aging， SBS degradation is more obvious， while in long-term aging， the asphalt phase hardening dominates.