沥青混合料紫外光老化评价指标的研究

Research on Evaluation Index of Ultraviolet Radiation Aging Bituminous Mixture

为了提出沥青混合料紫外光老化评价指标,通过沥青砂来研究沥青混合料的流变特性,制作沥青砂试件进行室内加速紫外光老化试验,分别进行0、2、4、6、8、12个月的紫外光老化。对老化的试件在恒定荷载0.1 MPa的作用下,保持恒定温度20℃进行单轴压缩蠕变试验,得到应变-时间关系曲线。采用Burgers模型描述沥青砂的流变性能,并根据应变-时间关系进行Burgers模型4参数的拟合,拟合得到不同老化时间对应的黏弹性参数值,对该值进行拟合,得到黏弹性参数和老化程度的关系式E1(h)、E2(h)、η1(h)、η2(h),把该表达式代入Burgers模型的本构方程表达的蠕变柔量方程中得到蠕变柔量J(t)和老化时间的关系式J(h,t),提出用J(h,1 200 s)作为沥青混合料紫外光老化的评价指标。

In order to put forward the evaluation index of ultraviolet radiation aging asphalt mixture, the rheological properties of asphalt mixture is researched through asphalt sand, asphalt sand specimens are made for laboratory ultraviolet radiation aging test for 0, 2, 4, 6, 8, 12 months. Keeping the constant pressure of 0. 1 MPa and the constant temperature of 20 ℃, the uniaxial compressive creep test is conducted to get the strain-time curve. The rheological properties of asphalt sand are expressed by Burgers model, the 4 parameters of Burgers model are fitted by the relation of strain-time to get the viscoelastic parameters corresponding to different aging time, and the viscoelastic parameters are further fitted to get the relations of E1 （h）,E2（h） ,η1（h） and η2 （h） about viscoelastic parameters and aging time. The relations are fed into the creep compliance equations expressed by the constitutive equation of Burger＇s model to get the relation J（h,t） about creep compliance J（t） and aging time, and J（h, 1200 s） is proposed as the ultraviolet aging evaluation index of asphalt mixture.