Multiscale Study on the Modification Mechanism of Red Mud Modified Asphalt

Tao Fu,Huiming Bao,Jianhui Wei,Junlin Liang

doi:10.1155/2020/2150215

Tao Fu, Huiming Bao + Show 2 more

Open Access

https://doi.org/10.1155/2020/2150215

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Abstract

Red mud, a waste residue of aluminium industry, was used as modified asphalt material to prepare red mud modified asphalt and red mud modified asphalt under freeze-thaw cycles. The matrix asphalt (MA), red mud modified asphalt (RMMA), and red mud modified asphalt under freeze-thaw cycles (RMMAFC) were studied by scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR), atomic force microscopy (AFM), and differential scanning calorimetry (DSC). Microscopic experiments were conducted to investigate the modification performance and mechanism. The modification mechanism of red mud modified asphalt was investigated using molecular dynamics simulation in this study. The results show that red mud can form a uniform and stable blending system with base asphalt after adding base asphalt. The structure of asphalt after adding red mud and adding red mud and freezing-thawing cycles does not change. The bee-structure decreases obviously with the addition of red mud by atomic force microscopy (AFM). Density decreases gradually, but bee-structure height increases obviously; bee-structure of red mud modified asphalt is destroyed after freeze-thaw cycles. Through differential scanning calorimetry (DSC), after adding red mud, heat absorption decreases. Freeze-thaw cycles greatly reduce heat absorption of red mud modified asphalt. Constructing molecular model of major components of red mud (Fe2O3, Al2O3) and asphaltene, simulation results show that the interfacial energy between asphaltene and red mud’s main components Fe2O3 and Al2O3 at −10°C, 25°C, and 170°C is stronger than that of Fe2O3. The results of calculating the interfacial energy of asphaltene on the chemical composition surface of red mud are negative. It can be seen that there are adsorption effects on the surface of asphaltene and red mud. Therefore, increasing the content of Al2O3 or decreasing the content of Fe2O3 in red mud is beneficial to the adsorption of asphaltene.

Highlights

By the end of 2019, China’s expressway has reached 4.85 million kilometers, ranking the first in the world
In the range of 600 cm−1 to 950 cm−1, it is called benzene ring substitution zone, the area where the aromatic components in asphalt are located. e substitution reaction occurs at different positions of benzene ring in the aromatic components. e change of absorption peak intensity indicates that substitution reaction may occur on benzene ring. e absorption peak intensity of base asphalt is stronger than that of freeze-thaw. e absorption peak strength of red mud modified asphalt under freeze-thaw cycles (RMMAFC) is higher than that of red mud modified asphalt (RMMA)
Red mud was used as modified asphalt material to prepare red mud modified asphalt and RMMAFC. e matrix asphalt (MA), RMMA, and RMMAFC were studied by scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR), atomic force microscopy (AFM), and differential

Summary

Introduction

By the end of 2019, China’s expressway has reached 4.85 million kilometers, ranking the first in the world. E rutting disease is directly related to the high temperature performance of asphalt and mixtures. It has always been a hot spot of pavement material research to use different modifiers to improve the high temperature performance of asphalt and improve the rutting resistance of pavement [2,3,4]. In view of the shortcomings of asphalt performance, researchers in various countries have studied the modification of asphalt by adding modifiers [5]. Researchers have found that inorganic material modifier can improve the interface between asphalt and aggregate and has the characteristics of simple production process, low price, excellent performance, and abundant reserves.

Experimental Design

Test Method

Results and Discussion

Conclusion