气相二氧化硅改性沥青的流变性能及改性机制

Rheological properties and mechanism of fumed SiO2 modified asphalt

纳米SiO_(2)(NS)可有效改善沥青的力学性能但价格高昂,气相SiO_(2)(FS)同样为纳米级材料且价格仅为NS的1/10。为评估FS代替NS的可行性,通过多重应力蠕变回复试验(MSCR)、线性振幅扫描试验(LAS)和弯曲梁流变试验(BBR)对比了普通SiO_(2)(OS)、FS、疏水纳米SiO_(2)(MNS)分别在掺量为3wt%时对基质沥青(Esso,ES)流变性能的影响。结果表明:FS对沥青高温抗车辙性能和中温抗疲劳性能的改善是三者中最好的,对低温抗裂性能的损害是最弱的。此外,借助SEM、变温红外光谱(VT-IR)、温度扫描(TeS)、TGA和DSC分析FS对沥青的改性机制,推断出FS特有的初级支化结构及其形成的“沥青-水团簇”体系是提升沥青性能的关键。因此,FS是一种性价比高的纳米级沥青改性材料。

Nano-silica(NS)modified asphalt is satisfactory in mechanical properties but is expensive.Fumed-silica(FS)is also a nanoscale material and the price is only 1/10 of NS.To evaluate the feasibility of FS replacing NS,using 3wt%original silica(OS),FS,hydrophobic nano silica(MNS)as modifier,the rheological properties of corresponding modified asphalt were studied compared with matrix asphalt(Esso,ES)by the multi-stress creep recovery test(MSCR),linear amplitude scanning test(LAS)and bent beam rheological test(BBR).The results show that the optimal modifier FS has the best effect on the rutting resistance at high temperature and the fatigue resistance at intermediate temperature for asphalt,and the least negative effect on the low temperature performance.The mechanism for these results was explored by SEM,temperature scanning test(TeS),variable temperature infrared spectroscopy(VT-IR),TGA and DSC.The intrinsic primary aggregates of FS and unique ES-hydroclusters system played a key role in the performance of FS-asphalt composite.Therefore,fumed SiO_(2) is a cost-effective nano-scale material used to modify asphalt.