考虑老化的沥青结合料低温感温性指标

为了验证不同老化程度沥青结合料的针入度指数IP、当量脆点T1.2与SHRP低温弯曲梁流变指标间的关系,选取3种常用重交基质沥青进行薄膜烘箱试验和不同时长的压力老化容器老化,测定不同老化程度沥青在不同较高温度的针入度,得到针入度温度指数AlgP、K、IP和T1.2;测定不同较低温度60 s时的弯曲梁流变指标S、m,得到低温蠕变温度指数AlgS和Am。通过试验得出:随着老化程度的增加,沥青的感温性降低,温度稳定性增加,T1.2呈升高趋势;对不同老化程度的沥青而言,其较高温度下的针入度温度指标AlgP、K与较低温度下的低温蠕变温度指标AlgS、KlgS、Am、Km之间具有较好的相关性;中国“八五”攻关专题中建议的沥青低温性能评价指标IP和T1.2与SHRP建议的低温性能评价指标S和m之间具有较好的相关性。

Low Temperature Susceptibility Indexes of Asphalt Binder with Different Aging Degree

In order to get the relationship among indexes(I_P, T_(1.2),S,m) of asphalt with different aging degree recommended by SHRP and the Eighth Five-Year National Plan in China,three kinds of heavy traffic unmodified asphalts were chosen for thin film over test(TFOT) and pressure aging vessel(PAV) test of different time.Then,the different origin and aging samples were experimented as follows:penetrations of asphalt with different aging degree were measured for the penetration temperature susceptibility indexes A_(lg P),K,I_P and T_(1.2).Bend beam rheometer indexes S and m values were also measured under different low temperature in 60 s so that low temperature creep indexes A_(lg S) and A_m could be gotten.Conclusions are drawn as follows: with the increasing of aging degree,temperature susceptibility of asphalt is weakened while temperature stability is enhanced and equivalent brittle point T_(1.2) is increased.For the asphalt with different aging degree,there are well linear correlations between A_(lg S) and A_(lg P),A_m and A_(lg P),K_(lg S) and K,K_m and K,S and I_P,m and I_P,S and T_(1.2),m and T_(1.2) by regression.