Modification effects of nanosilica on asphalt binders: A review

Nanosilica (NS) may be obtained as a by-product in several industrial processes and is associated with high availability and affordability among other nanoadditives. NS has been used for asphalt modification, and improvement in high-temperature performance and several other physical properties has been reported. However, due to the wide varieties and intrinsic variability of asphalt materials, concerns have been raised about the reproducibility of some conclusions, and therefore, a review was conducted. According to the results, NS additives with a purity of over 99% were usually used for modification and the specific surface area was over 100 m(2)/g, leading to the superior absorption of asphalt and thus improvement in rutting resistance of the mixtures. Due to a lack of guidance for the blending procedures, inconsistency exists among studies in the shear speed, blending duration, and temperature, leading to possible excessive blending and unnecessary energy and time consumption. Rises in NS concentration would cause higher softening point and rotational viscosity, and therefore elevated temperatures for mixing and paving, but penetration would be reduced. According to rheological evaluations, with the rise of NS concentration, the rutting parameter would increase, indicating an improvement in the high-temperature performance, but the low-temperature performance may deteriorate.

Automated summary

Nanosilica (NS) has been widely used as an additive in asphalt modification to improve its performance. However, there are concerns about the reproducibility of the results due to the variability of asphalt materials. High-purity NS additives with a large specific surface area have been found to be effective in enhancing the rutting resistance of asphalt mixtures. Inconsistency in blending procedures, such as shear speed, blending duration, and temperature, can lead to excessive blending and unnecessary energy and time consumption. Increasing the concentration of NS can affect the physical properties of asphalt, resulting in improved high-temperature performance but potentially deteriorated low-temperature performance.