Investigation of the Microcharacteristics of Asphalt Mastics under Dry–Wet and Freeze–Thaw Cycles in a Coastal Salt Environment

Abstract

In the coastal areas of southeastern China, high temperatures and humidity in the summer and microfreezing in the winter, as well as a high concentration of salt spray in the environment, seriously deteriorate the durability of asphalt mixtures. Therefore, the microcharacteristics of asphalt mastics (asphalt mixed with mineral filler) under the effect of chlorine salt and “dry–wet and freeze–thaw” (DW-FT) cycles were investigated by Fourier-transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), and atomic force microscopy (AFM) techniques. Two factors, including asphalt mastic types (base and styrene-butadiene-styrene (SBS)-modified mastics) and numbers of DW-FT cycles, were considered based on the natural environment. Regression functions were established to explore the relationship between the FTIR, GPC, and AFM indexes. The results indicate that there were no chemical reactions between the asphalt and filler because the infrared spectrum of the base and SBS-modified mastics were similar. With the increase of the salt “DW-FT” cycle numbers, the sulfoxide index and large molecular size ratios ( L M S % ) increased, and the surface roughness ( R q and R a ) of the morphology decreased, as illustrated by a flatting mastics surface phenomenon in the AFM test. Regression analysis confirmed that there was a high correlation between the FTIR, GPC, and AFM indexes, and formation of the bee structures was closely related to the long chain index. The SBS-modified mastics had a better antiaging performance with a lower increase in the sulfoxide index after the salt “DW-FT” cycles in the coastal environment.

Effect of Nanoclays on Moisture Susceptibility of SBS‐Modified Asphalt Binder

“…Roughness is an index used to evaluate the undulation of the surface microstructures [31,61,62]. Considering the effects of water, there is no definite rule in the change in roughness that may occur as a result of water contact.…”

“…Considering the effects of water, there is no definite rule in the change in roughness that may occur as a result of water contact. e asphalt type, modifier type, aging effects, probe type, and other factors will all affect the changes in roughness that occur in the presence of water [31,39,62,63].…”

Performance Deterioration of Asphalt Mixture under Chloride Salt Erosion

“…Guo et al explored the interface bonding property between asphalt and aggregate subjected freeze-thaw cycles and salt solution erosion through pull-off tensile tests considering different test temperatures [ 15 ]. Zhang et al studied the influences of chlorine salt and freeze-thaw cycles on asphalt mastics from the perspective of spectroscopic and characteristics by using Fourier-transform infrared spectroscopy, gel permeation chromatography, and atomic force microscopy techniques [ 25 ]. Amini et al investigated the influences of moisture and chloride salt on the performance degradation of asphalt mixture subjected to freeze-thaw cycles according to the Marshall stability and mass loss [ 26 ].…”

Study on Performance Damage and Mechanism Analysis of Asphalt under Action of Chloride Salt Erosion

“…At the same time, the freeze–thaw cycle test of a salt solution was simulated [ 23 ]. Zhang et al studied the influences of chlorine salt and freeze–thaw cycles on asphalt mastics from the perspective of microscopic characteristics by using Fourier transform infrared spectroscopy, gel permeation chromatography, and atomic force microscopy techniques [ 24 ]. The above research shows that salt erosion can significantly reduce the performance of asphalt itself, leading to the decrease in the bonding effect of the asphalt binder, and then affect the adhesion between the asphalt and aggregate.…”