Contact erosional behaviour of foundation of pavement embankment constructed with nanosilica-treated dispersive soils

Abstract

To overcome the problems associated with the construction of pavement layers on soft subgrade, working platforms constructed with granular soils are normally placed beneath the overlying paving layers. Sometimes, the embankment layer located between the pavement and the working platform layers may have dispersive nature. In such case, the dispersive soil particles can be easily transported through the large pores of the working platform layer under water movement, resulting in soil loss of the dispersive embankment and the subsequent settlement of the pavement layers. In other words, dispersive soils are susceptible to contact erosion. Therefore, the contact erosional behaviour of the dispersive embankment layer placed on granular materials must be investigated. In the current study, the contact erosion of both the dispersive embankment and also the nanosilica-treated dispersive embankment cured for periods of up to 28 days was investigated experimentally under the vertical flow of groundwater. The significant mass loss was measured when the embankment layer was highly dispersive. However, the mass loss decreased by treating the dispersive embankment layer using an environmentally friendly stabilizer named nanosilica, which reflected the high potential use of the nanosilica to improve the dispersive soils. Besides, it was verified by the Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR) spectra tests on the natural dispersive soil samples and the ones after being treated by nanosilica. The plasticity index decreased and unconfined compressive strength increased due to addition of nanosilica to the dispersive soil; thus, its workability improved. The dispersion and contact erosion tests results indicated that there was a very good correlation between dispersivity potential and some contact erosion assessment parameters, such as void ratio, collected eroded soil and settlement. In conclusion, the contact erosion rate can be estimated based on the relationships proposed in this study.