添加剂型高模量沥青混合料作用机理
Mechanism research on additives of high modulus asphalt mixtures

高模量沥青混合料以其优异的抗车辙效果而广受关注，尤其是添加剂型高模量沥青混合料，然而添加剂对沥青混合料性质的影响作用机理尚不明确。以傅里叶红外光谱仪(FIR)、沥青抽提仪、扫描电子显微镜(SEM)、动态剪切流变仪(DSR)、研究高模量添加剂在沥青混合料中的作用机理。通过FT-IR官能团分析添加剂对沥青的影响，分析添加剂与石料的相互作用及沥青混合料性能，对高模量添加剂添加前后的沥青粘弹特性差异及沥青混合料性能进行对比分析。研究结果表明：长链脂肪族碳链的酯类与聚烯烃接枝复配的添加剂，不损伤沥青混合料低温抗裂性；拌和时熔点在150 ℃~160 ℃，粒径较小的添加剂Ｂ与热集料(180 ℃~190 ℃)碰撞、被剪切并熔融分散，沥青抽提后其在石料表面残留少，贡献率较高；SEM图像显示添加剂Ｂ在沥青中分散均匀，且灰度直方图的灰度值较集中；DSR 研究发现，熔融的添加剂使沥青弹性模量G’增大，相位角δ降低，粘度增大，改善了沥青流变特性；少量未熔融颗粒碾压时嵌挤入混合料空隙中，增大了混合料内摩阻角，提高了沥青混合料的模量。
High modulus asphalt mixtures have incurred a lot of attention because of great anti-rutting performance, especially additive-type high modulus asphalt mixtures. However, the effect of additive on the performance of asphalt mixture is still unknown. This paper investigated the mechanism of high modulus additives in the hot asphalt mixtures (HAM) by means of Fourier infrared spectrometer (FIR), asphalt extractor, scanning electron microscope (SEM) and dynamic shear rheometer (DSR). By analyzing the effect of additives on asphalt through FT IR functional group, the interaction between additives and asphalt mixtures, and the properties of asphalt mixtures, this paper investigated and compared the difference of asphalt viscoelastic behavior before and after adding high modulus additives and the properties of asphalt mixtures. The results show that esters with long fatty group carbon chain and polyolefin are useful constituents to improve low-temperature performance of hot asphalt mixtures. When mixing additive B melts and disperses in hot aggregate (180 ℃~190℃) by colliding and shearing, its aggregate surface after extraction has little residual additive because of smaller grain size and right melting point (about 150 ℃~160 ℃). So it makes more contribution than A. The SEM image shows that B is well-distributed in asphalt binder, displaying a centralized grey value in gray level histogram. DSR shows that asphalt binders which is added high modulus additives improves binder s viscoelastic behaviors, and obtains higher storage modulus G′, lower phase angle δ and higher viscosity. Few unmelted additives interlock into mixtures voids during compaction, which increases mixtures internal friction angle and asphalt mixtures modulus