铁尾矿砂沥青混合料的高温性能

High-temperature performance of iron tailings asphalt mixture

为了考察铁尾矿砂沥青混合料(iron tailings asphalt mixture,IT-AM)高温性能随铁尾矿砂体积掺量的变化规律,设计了不同铁尾矿砂体积掺量的沥青混合料,并进行马歇尔试验、高温车辙试验、高温浸水车辙试验和动态模量试验,研究IT-AM的马歇尔稳定度和流值、高温蠕变及其动稳定度(dynamic stability,DS)、水温耦合蠕变及其DS、动态模量和相位角随铁尾矿砂体积掺量的变化规律。结果表明:铁尾矿砂的主要化学成分为SiO_(2),属酸性集料;由于铁尾矿砂比天然细集料具有更多的微裂缝,吸附了部分沥青,因此IT-AM的沥青用量较大;IT-AM的60℃马歇尔稳定度、高温DS、水温耦合DS、动态模量和相位角均随着铁尾矿砂体积掺量的增加而降低,而流值、高温蠕变和水温耦合蠕变均随着铁尾矿砂体积掺量的增加而增大,说明铁尾矿砂体积掺量越大,IT-AM的高温性能越差;铁尾矿砂替代天然细集料的体积掺量不宜超过40%,方可满足高温性能要求。

In order to investigate the variation of high-temperature performance of iron tailings asphalt mixture(IT-AM)with iron tailings volume content,the asphalt mixture with different volume contents of iron tailings was designed,and Marshall test,high-temperature rutting test,high-temperature soaking rutting test and dynamic modulus test were carried out.The variations of the Marshall stability and flow value,high-temperature creep and its dynamic stability(DS),water temperature coupling creep and its DS,dynamic modulus and phase angle of the IT-AM with the volume content of iron tailings were studied.The results show that the main chemical component of iron tailings is silica,which belongs to acidic aggregate,because iron tailings have more micro cracks than natural fine aggregates and absorb part of the asphalt,the asphalt content of the IT-AM is larger.The 60℃Marshall stability,high-temperature DS,water temperature coupling DS,dynamic modulus and phase angle of the IT-AM decrease with the increase of iron tailings volume content,while flow value,high-temperature creep and water temperature cou-pling creep are all with the iron tailings volume content.It means that the larger the iron tailings volume content,the worse the high-temperature performance of the IT-AM.The volume content of iron tailings instead of natural fine aggregate should not ex-ceed 40%in order to meet the high-temperature performance requirements.