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High-temperature rutting is one of the common forms of pavement damage. To further improve the high temperature performance of crumb rubber modified asphalt (CRMA) pavement, heavy calcium carbonate (HCC) modified by sodium pyrophosphate was combined with crumb rubber to prepare composite modified asphalt binder. Their physical properties, viscoelastic properties and chemical composition were investigated through conventional physical tests, DSR, FTIR and fluorescence microscopes. The results show that with the increase of HCC content, the mixing and compaction temperatures of composite modified asphalt binders continued to increase. Further, the high temperature performance and fatigue resistance of binders were better than the original CRMA, due to the enhanced lipophilicity of HCC after modification. It can be found from the FTIR spectrum that the addition of HCC only existed in physical action. However, excessive HCC would cause agglomeration of the asphalt matrix, so the optimum dosage of HCC was determined to be 4%. [ABSTRACT FROM AUTHOR]

To reduce vehicle exhaust gas pollution in transport-intensive roadways and tunnels, six types of photocatalytic asphalt binders were designed using graphite-phase carbon nitride (g-C3N4) and nanoscale titanium dioxide (nano-TiO2) particles. In this paper, the rheological behaviors and fatigue life of the nano-TiO2-modified asphalt binder (TiO2-MA) and g-C3N4-modified asphalt binder (C3N4-MA) were investigated. NO degradation capacity of six types of photocatalytic asphalt binders was characterized under visible light conditions. The results showed that TiO2-MA had more excellent rheological behaviors and rutting resistance than C3N4-MA. In addition, 4 wt% nano-TiO2 markedly improved the rheological behaviors and rutting resistance of MA compared to other dosages. TiO2-MA exhibited higher fatigue resistance. The fatigue life of TiO2-MA with 4 wt% nano-TiO2 was increased to 234.1% at 2.5% strain and 242.5% at 5% strain, respectively, compared to base asphalt binder (BA). C3N4-MA had better NO degradation capacity than TiO2-MA. Meanwhile, the NO degradation efficiency of C3N4-MA reached 17.8% with 5 wt% g-C3N4. [ABSTRACT FROM AUTHOR]

Near the coast of China, a large amount of sediment is produced during construction work. In order to mitigate the environmental damage caused by sediment and enhance the performance of rubber-modified asphalt effectively, solidified silt material and waste rubber were prepared to modify asphalt, and its macroscopic properties, such as viscosity and chemical composition, were determined via a routine physical test, DSR, Fourier Transform Infrared Spectroscopy (FTIR), and Fluorescence Microscopy (FM). The results show that, with the increase in powder particles and the addition of a certain amount of hardened mud, the mixing and compaction temperature of modified asphalt can be significantly increased—still reaching the design standard. In addition, the high thermal stability and fatigue resistance of the modified asphalt were clearly better than those of the ordinary asphalt. From the FTIR analysis, rubber particles and hardened silt only exhibited mechanical agitation with the asphalt. Considering that excessive silt might result in the aggregation of matrix asphalt, the addition of an appropriate amount of hardened solidified silt material can eliminate the aggregation. Therefore, the performance of modified asphalt was optimum when solidified silt was added. Our research can provide an effective theoretical basis and reference values for the practical application of compound-modified asphalt. Therefore, 6%HCS(6:4)-CRMA have better performance. Compared to ordinary rubber-modified asphalt, the composite-modified asphalt binder has better physical properties and a more suitable construction temperature. The composite-modified asphalt uses discarded rubber and silt as raw materials, which can effectively protect the environment. Meanwhile, the modified asphalt has excellent rheological properties and fatigue resistance. [ABSTRACT FROM AUTHOR]

Cow dung waste has caused severe environmental pollution and public health issues in China. In this study, the cow dung residues were used as a cheap renewable fiber to modify asphalt binder, providing a new solution for the proper disposal of cow dung waste. Three cow dung fibers with two lengths were prepared using different treatments, including original cow dung fiber (CDF), surface treatments of cow dung fiber (STCDF) and alkali treatments of cow dung fiber (ATCDF). The physicochemical properties of CDF, STCDF and ATCDF were analyzed by scanning electron microscope (SEM) and thermogravimetry (TG). The viscidity, rheological properties and fatigue characteristics of CDF modified asphalt binders (CDFMA) were evaluated using Brookfield viscometer and dynamic shear rheometer. The results showed that the rough surfaces of STCDF and ATCDF improved their thermal stability. STCDF and ATCDF enhanced the resistance to permanent deformation under high temperature conditions of modified asphalt binder. STCDF modified asphalt binders exhibited the best viscosity and rheological performance. The increase of fiber length was positively correlated with the high temperature deformation resistance of CDFMA. CDF, STCDF and ATCDF inhibited fatigue cracking of modified asphalt binders compared to base asphalt binders. ATCDF modified asphalt binders exhibited higher fatigue life and smaller crack under the same cyclic loading. The increase in fiber length had a slight improvement on the fatigue resistance of modified asphalt binders. [ABSTRACT FROM AUTHOR]

• Quantitative determination for SBS content of aged modified asphalt by FTIR and potentiometric titration tests. • The rheological properties were investigated after TFOT and long-term aging of modified asphalt. • The actual SBS content versus the rheological indexes of aged modified asphalt can be well-fitted. The content of styrene–butadiene–styrene (SBS) modifier has a significant influence on the physical and chemical characteristics of asphalt. However, determining the SBS content in SBS modified asphalt (SBS MA) after aging remains a challenge. To facilitate the understanding of the relationship between physical properties and SBS content, the Fourier transform infrared (FTIR) and potentiometric titration test were utilized to detect SBS content of aged binders. In this paper, radial and linear SBS were incorporated into asphalt binders at three levels, and their rheological properties were investigated after thin film oven aging (TFOT) and long-term aging. Furthermore, the actual SBS content versus the rheological index at different aging stages was investigated. The results showed that both I C=C and Na 2 S 2 O 3 titration volume highly correlated with SBS content (R2 > 0.99), and there was only a slight difference between the actual content of SBS determined by the two methods. The fatigue resistance, high-temperature elastic, and low-temperature cracking characteristics of asphalt were weakened after aging, due to SBS degradation, especially in the early stage. In addition, the resistance to deformation, elastic recovery, anti-fatigue properties of radial SBS MA were superior to that of linear SBS MA at the same SBS content, while the low-temperature cracking performance demonstrated an opposite trend. The actual SBS content versus the rheological indexes after aging can be well-fitted by a nonlinear equation. Therefore, FTIR and potentiometric titration tests can effectively predict SBS content and analyze the aging degree of SBS MA. [ABSTRACT FROM AUTHOR]