沥青针入度指数的研究

Study on Penetration Index

回顾了针入度指数PI 的历史 ,探讨了PI 的应用基础和适用范围 ,PI 应用基础是沥青的针入度的对数与相应的温度之间存在线性关系的这一假设 ,中国的规范中PI 是根据一个不同温度下的针入度回归出来的 ,不同于欧洲的计算方法 ;通过实验与分析发现 ,如果根据中国的规范方法计算PI,PI 受是否预冷、温度及温度个数等因素的影响 ,针入度在允许误差范围内的变化会引起PI 更大的波动 ,回归时很高的相关系数并不能说明由试验数据回归的PI 是可信的 ,由于改性沥青的针入度的对数与相应的温度之间不再是线性关系 ,PI 用于评价改性沥青的感温性能有一定的局限性 .

Firstly,a brief review about penetration index (P_I) is given.It is generally believed that P_I is based on the hypothesis that there is linear relationship between the temperature and the logP and P_I is only affected by asphalt itself.According to Chinese specification,P_I value regressed based on the penetration results with five different temperatures,which is different from European specification.According to test result and data analysis in the paper,it is found that P_I value predicted by Chinese specification is affected by many factors rather than bitumen itself.Besides,the value of P_I is sensitive to the penetration error.So in the regression process of P_I value,the high estimation accuracy does not indicate the P_I value can be really predicted by this method.For polymer-modified asphalt (PMA),there is no linear relationship between the temperature and the logP,so it is unreliable to evaluate the performance of PMA by P_I.