聚氨酯多孔弹性混合料水稳定性影响因素研究

Study on the Influencing Factors of Water Stability of Polyurethane Porous Elastic Mixture

聚氨酯多孔弹性混合料(PPEM)由聚氨酯黏结剂、橡胶颗粒和石料组成,相较于普通沥青混合料具有空隙率大、橡胶颗粒掺量高等特点。由于PPEM是大孔隙结构,使得雨天雨水易流入路面内部,进而引发水损害。为此,基于浸水马歇尔试验、冻融劈裂试验和浸水飞散试验,分别测试不同聚氨酯黏结剂、橡胶颗粒替换量、级配3种工况下PPEM的水稳定性。结果表明:对比分析不同聚氨酯黏结剂多孔弹性混合料,其中PU-III多孔弹性混合料水稳定性最好,PU-IV多孔弹性混合料水稳定性最差;当橡胶颗粒替换量不断提高时,PPEM的马歇尔残留稳定度和抗拉强度比呈线性增长,说明橡胶颗粒对PPEM水稳定性的提高有促进作用;PPEM所用级配的空隙率与其水稳定性呈负增长,水稳定性随空隙率增大而减小。

Polyurethane porous elastic mixture(PPEM)is composed of polyurethane adhesive,rubber particles and aggregate.Compared with ordinary asphalt mixture,PPEM has the characteristics of large void ratio and high content of rubber particles.Because the PPEM is a macroporous structure,the rainwater is easy to flow into the pavement in rainy days,and then cause water damage.Based on the immersion Marshall test,freeze-thaw split test and immersion dispersion test,the water stability of polyurethane mixture under three conditions of different polyurethane binder,different rubber particle content and different gradation was tested.The results show that the water stability of porous elastic mixture with different polyurethane binder is compared,PU-III porous elastic mixture has the best water stability and PU-IV porous elastic mixture has the worst water stability.With the increase of rubber particle replacement amount,Marshall residual stability and freeze-thaw splitting strength ratio of PPEM increase gradually,which shows that the addition of rubber particle is beneficial to improve water stability of PPEM.The correlation between the void fraction of the gradation used in PPEM and its water stability is negative,the water stability decreases with the increase of the void fraction.