长期浸水作用对沥青混合料粘聚性的影响研究

Research on Influence of Long Term Immersion to Cohesiveness of Asphalt Mixture

将现场取芯的上、中、下面层的沥青混合料试件分组并长期放置于水中,每隔3个月测定试件的质量吸水率,采用劈裂试验及无侧限抗压强度试验测定试件的劈裂抗拉强度、粘聚力和内摩擦角,运用2种拟合方法对沥青混合料试件粘结力和内摩擦角变化趋势进行拟合.结果表明,沥青混合料试件初期阶段吸水率迅速增加,后期水分进入微空隙,吸水率增加缓慢;试件劈裂抗拉强度随浸水时间的增加而减小;长期水作用下沥青膜与集料之间粘附性下降,粘聚力随浸水时间增加大致呈线性变化,内摩擦角随浸水时间变化大致呈2次抛物线变化.

The drilling core asphalt mixtures of the upper,middle and lower layers are grouped and placed in water for long time and the water absorption rate of the specimen is tested every three months.Split test and unconfined compression strength test are used to measure the splitting tensile strength,the cohesion and internal friction angle.Two fitting methods are used to fit the trend of the change of cohesion and internal friction angle.The test results show that the water absorption rate of the asphalt mixtures is increased rapidly at early stage.Moisture enters the micropores,resulting in that the water absorption rate of the asphalt mixtures increase slowly at the later stage.The splitting tensile strength of the asphalt mixture is decreased with the increase of immersion time.Under longterm immersion,the adhesion between asphalt membrane and aggregate is decreased.As the increase of immersion time,the trend of the change of cohesion is approximately a linear change and the trend of the change of internal friction angle is generally aparabolic variation.