基于黏弹性理论的多聚磷酸改性沥青低温性能

基于黏弹性理论,对不同质量分数(0.5wt%,1.0wt%,1.5wt%,2.0wt%)的多聚磷酸改性沥青及基质沥青进行低温弯曲流变试验(BBR),结合Burgers模型对低温弯曲梁流变试验得到的蠕变数据进行非线性拟合,利用Burgers模型的四个参数(E_1、η_1、E_2、η_2分别是Maxwell和Kelvin模型中弹性模量和黏性系数)确定出低温性能指标,对多聚磷酸改性沥青低温性能进行分析。结果表明:多聚磷酸的添加使沥青中的黏性和弹性都得到了一定的改善,沥青中松弛时间减少,储存能减少,耗散能增加,应力松弛能力得到提高。在相同温度下,多聚磷酸改性沥青延缓了沥青进入蠕变稳定期的时间,但随着温度的降低,达到蠕变稳定期的时间缩短。多聚磷酸改性剂的添加可以提高沥青低温性能,且随质量分数的增加,低温改善效果更好;但随着温度的降低,多聚磷酸对沥青的低温改善程度减小,且不同质量分数对其影响的差异也减小,在-24℃以上适合使用多聚磷酸改性,而在-24℃以下掺入多聚磷酸改性沥青意义不大。

Low temperature performance of polyphosphoric acid asphalt based on viscoelastic theory

Based on viscoelastic theory,the low temperature bending beam rheometer test (BBR)of asphalt with different mass fractions of poly phosphoric acid (PPA)modification (0.5wt%,1.0wt%,1.5wt%,1.0wt%)were carried out.The creep data from the low temperature BBR test was nonlinearyly fitted using the Burgers model,and low temperature performance index was determined using the four parameters of Burgers model(E1 ,η1 ,E2 andη2 Maxwell and Kelvin model of elastic modulus and viscosity coefficient),and so the low temperature performance of the PPA modified asphalt was analyzed.The results shows that the addition of PPA improves the viscosity and elasticity of asphalt,the relaxation time decreases in the asphalt,the stored energy reduces,the dissipation energy increases,and the stress relaxation ability is improved.At the same temperature,the PPA modified asphalt delays the time of asphalt into the creep stability period,but it was shortened with the temperature decreasing.The low temperature performance of asphalt improves with the addition of PPA,and the effect is better with more PPA contents.But the improvement degree reduces with the decrease of the temperature,and the differences between the effects of different mass fractions also become smaller.The PPA is suitable at the temperature above -24 ℃,while it is meaningless below -24 ℃.