养生作用对硫沥青性能影响分析

硫磺部分替代传统石油沥青用于道路工程建设可减少石油沥青用量，降低施工能源消耗，促进工业废渣中硫磺的回收利用，具有较高的经济和环保价值。为探究硫磺掺量（质量分数）及养生作用对硫沥青（SEA）性能的影响，采用差示扫描量热仪（DSC）验证硫沥青中硫磺的重结晶现象，对养生前后硫沥青的基本物理性能和黏度进行分析，并采用动态剪切流变仪（DSR）和弯曲梁流变仪（BBR）对养生前后硫沥青的流变特性和疲劳性能进行评价，最后借助荧光显微镜（FM）观察养生前、后硫磺在沥青中的微观分布特性。研究结果表明：养生后高硫磺掺量的硫沥青DSC曲线出现吸热峰，硫沥青（特别是高硫磺掺量下）的劲度有所增加，因此对硫沥青进行养生使其性能稳定后再进行相关性能评价更具现实意义；硫磺掺量较低（≤ 10%）时，硫磺主要以溶解硫的形式存在于沥青中起到软化沥青的作用，因此沥青的低温变形能力有所改善，但其高温抗变形能力有所降低；当硫磺掺量较高（≥ 35%）时，硫磺主要以重结晶的形式悬浮在沥青中使沥青变硬，在增加沥青高温抗变形能力的同时也牺牲了其低温抗裂能力；硫磺掺量较低时，硫沥青黏度随着硫磺掺量的增加而降低；硫磺掺量较高时，硫沥青90℃和105℃黏度随着硫磺掺量的增加而增加，但硫沥青120℃和135℃黏度相差不大，同时硫磺加入最高可降低沥青的施工温度达20℃；线性振幅扫描（LAS）试验结果表明，养生后的硫沥青疲劳寿命比基质沥青长，其中35%硫沥青疲劳性能最佳；硫磺掺量进一步增加，硫沥青疲劳寿命缩短至与基质沥青相近；FM分析表明，硫磺掺量不高于5%时，硫磺全部溶解于沥青中，且养生后硫磺未重结晶，相应硫沥青无荧光性；硫磺掺量高于5%时，硫磺在沥青中分布均匀，养生后10%硫沥青中硫晶斑尺寸和面积显著增大，高硫磺掺量硫沥青中硫晶斑面积仅略有增加。

Effect of Curing on Performance of Sulfur Extended Asphalt

Using sulfur to partially replace the conventional petroleum-based asphalt in road construction can reduce the petroleum-based asphalt and energy consumption, and promote the recycling of sulfur from waste residue, thus achieve a high economic and environmental benefit. This paper investigated the effect of sulfur dosage and curing time on the properties of sulfur extended asphalt (SEA). The differential scanning calorimeter (DSC) was used to help verify the phenomenon of sulfur recrystallization in SEA. The basic physical properties and viscosity of SEA before and after curing were analyzed, and the Dynamic Shear Rheometer (DSR) and the Bending Beam Rheometer (BBR) were applied to evaluate the rheological characteristics and fatigue performance of SEA, finally, fluorescence microscope (FM) was used to observe the sulfur distribution in SEA before and after curing. Related results indicate that the DSC curves of SEA with high sulfur content have endothermic peak and that SEA become stiffener after curing (especially with high sulfur dosage), so it is more reliable to evaluate the performance of SEA when its properties become stable after curing. Sulfur will mainly dissolve into and soften the asphalt when the sulfur dosage is low (≤ 10%), which enhances SEA's low-temperature performance but sacrifices its deformation resistance at high temperature to some extent. Sulfur recrystallization mainly exists in SEA with high sulfur dosage (≥ 35%), which hardens the asphalt and increases its deformation resistance at high temperature but leaves poor low-temperature cracking resistance. The viscosity of SEA decreases with the increase of sulfur dosage when the sulfur content is low. However, with a high dosage of sulfur, the viscosity of SEA at 90℃ and 105℃ increases with the increase of sulfur dosage while it shows little change at 120℃ and 135℃. Meanwhile, the mixing and compacting temperatures can be reduced by up to 20℃. The Linear Amplitude Sweep (LAS) test results show that the fatigue life of SEA after curing is longer than that of base asphalt, among which, the 35% SEA shows the highest fatigue life, and with the increase of sulfur dosage, the SEA fatigue life is shortened to that of base asphalt. FM analysis shows that all sulfur dissolves into the asphalt and does not recrystallize after curing when the sulfur dosage is no higher than 5%, and the corresponding SEA has no fluorescence. The distribution of sulfur in asphalt is uniform when the sulfur dosage is higher than 5%, which can ensure the performance stability of SEA. After curing, the sizes and area of sulfur crystal spots increase significantly in 10% SEA but only increase slightly for SEA with high sulfur dosages.