Multiwalled Carbon Nanotube Aided Fly Ash-Based Subgrade Soil Stabilization for Low-Volume Rural Roads

The impact of multi-walled carbon nanotubes (MWCNT) and fly ash on poor subgrade soil is studied in this research. The materials used in the study were comprehensively characterized using microstructural techniques. Apart from basic atterberg limit tests, modified proctor tests, unconfined compressive strength tests (UCS), and soaked California bearing ratio tests (CBR) were performed on different soil samples. The soil samples were subsequently replaced with 0, 20, 20, 30, 40, and 50% of fly ash, respectively. The different soil samples were mixed with water doped with 1:1000, 1:100, 1:10, and 0, respectively. Sodium Hexametaphosphate (1% w/w) is also used in conjunction with MWCNT to improve their dispersion in an aqueous medium. Ultrasonication of the aqueous medium was also done to further improve the dispersion of the MWCNTs in the aqueous medium. The UCS and CBR values were increased with the increase in the fly ash content up to 20%. 1:100 w/w doping of water with MWCNT yielded the best results. The use of 1:100 w/w with 20% replacement of soil with fly ash can lead to a good grade subgrade for low-volume rural roads. The uniqueness of this study is the use of MWCNTs in absence of any form of cement.