疏水性纳米白炭黑对沥青胶结料低温性能的影响

Effects of Hydrophobic Nano-Silica on the Low-Temperature Performance of Asphalt Binder

为研究疏水性纳米白炭黑对沥青胶结料低温性能的影响,应用常规沥青低温性能试验和胶浆小梁弯曲试验对比评价疏水性纳米白炭黑改性沥青、纳米白炭黑改性沥青和90#基质沥青的低温性能,通过扫描电镜分析两种改性材料的特点与改性机理,基于微观分析结果,采用傅里叶红外光谱研究改性材料对沥青低温性能的增强机理。结果表明,疏水性纳米白炭黑改性沥青的针入度指数PI值最大,其低温脆点比纳米白炭黑改性沥青低80%,-15℃时最大弯拉应变比基质沥青高350%,比纳米白炭黑改性沥青高80%。-15℃时极限弯拉强度比基质沥青高69%,低温性能优异;疏水性纳米白炭黑颗粒尺寸比纳米白炭黑小11%,粒径分布更均匀,颗粒表面为有机性且更粗糙,拌合不易聚团,改性颗粒与沥青构成三维网格型受力结构,改善了沥青低温受力特性;疏水性纳米白炭黑与沥青之间生成了C—O化学键,增强了改性材料颗粒与沥青的粘结,强化学粘结缩短了沥青拉伸链长度使变形能力增加。

The low-temperature performances of 90#asphalt,nano-silica modified asphalt and hydrophobic nano-silica modified asphalt were comparatively evaluated with low-temperature performance test of conventional asphalt and bending test of small mortar beam in order to investigate the effect of the hydrophobic nano-silica on the low-temperature performance of asphalt binder.Scanning electron microscope test were conducted to analyze the chara-cteristics and modification mechanism of the two kind of modified materials.Then the Fourier transform infrared spectroscopy test was conducted to study the function mechanism of modified asphalt to improve low-temperature performance of asphalt.Research results show that:the penetration index of hydrophobic nano-silica modified asphalt is the highest;its equivalent brittle point is 80%lower than that of nano-silica modified asphalt;its maximum flexure tensile strain is 80%higher than that of nano-silica modified asphalt and 350%higher than that of matrix asphalt at-15℃;its ultimate flexural tensile strength is 69%higher than that of matrix asphalt at-15℃,which indicates that the low temperature performance of hydrophobic nano-silica modified asphalt is excellent.Hydrophobic nano-silica particle is 11%smaller than nano-silica particle,and the size distribution of hydrophobic nano-silica particle is more uniform.The surface of hydrophobic nano-silica particle is organic.Compared with nano-silica particle,the surface of hydrophobic nano-silica particle is rougher.Hydrophobic nano-silica particle is not easy to gather when modified mixing.The three-dimensional mesh structure formed by modified particles and asphalt improves the low-temperature characteristics of asphalt.The C—O chemical bond is formed between hydrophobic nano-silica and asphalt,which enhances the bond between modified particles and asphalt,and the strong chemical bond shortens the length of asphalt tensile chain which results in an increase in the deformation ability.