Road Performance and Modification Mechanisms of Disintegrated Carbonaceous Mudstone Modified with Gum Arabic

The aim of this study is to improve the road performance of disintegrated carbonaceous mudstone, enabling it to qualify as an embankment filler. For this purpose, disintegrated carbonaceous mudstone was modified with gum arabic, and the road performance of the modified disintegrated carbonaceous mudstone and its modification mechanisms were analyzed. The effects of the gum arabic content and curing duration on the road performance were examined using the California bearing ratio (CBR), resilient modulus, unconfined compressive strength (UCS), and uniaxial tensile test. The physicochemical property changes of the disintegrated carbonaceous mudstone before and after modification were analyzed by measuring the disintegration, pH, conductivity, total dissolved solids, and zeta potential. The mechanism by which the gum arabic modified the disintegrated carbonaceous mudstone was explored using scanning electron microscopy, X-ray energy dispersive spectroscopy, and Fourier-transform infrared spectroscopy. The results of the study show that gum arabic effectively improves the road performance of disintegrated carbonaceous mudstone, and the degree of improvement gradually increases with increasing dosages and maintenance age. From an economic perspective, the best modification effect on road performance is achieved when the gum arabic dosage is 4% at which point the CBR and resilient modulus increase by 495% and 427%, respectively, and the UCS and uniaxial tensile strength increase by more than 230%. Gum arabic significantly reduces the disintegration rate, pH, conductivity, TDS, and absolute zeta potential of disintegrated carbonaceous mudstone, thereby improving its water stability. Moreover, the internal structure of the modified disintegrated carbonaceous mudstone is optimized by reducing its alkalinity, thus facilitating ion exchange between the cations and ions on the particle surfaces. Furthermore, the cohesion and integrity improve through the cementing of disintegrated carbonaceous mudstone particles, filling of internal pores, and encapsulation of surface layer particles and agglomerates to block the direct action of the external environment. The research results provide possibilities for the reuse of disintegrated carbonaceous mudstone and a reference for the application of gum arabic as a modifier for other geotechnical materials. © 2023 Xi'an Highway University. All rights reserved.