Mechanism of stabilized/solidified heavy metal contaminated soils with cement-fly ash based on electrical resistivity measurements

Abstract The present work aimed at investigating the S/S micro-mechanism for treating heavy metal contaminated soils by an electrical resistivity method. Results indicated that the electrical resistivity ( ρ ) increased as a function of curing time and decreased as the heavy metal concentration increased. Unconfined compressive strength ( q u ) has an exponential correlation to the electrical resistivity. The variations of the electrical resistivity parameters (such as pore water electrical resistivity ( ρ ω ), formation factor ( F ), shape factor ( f ) and anisotropy coefficient ( A )) indicated that increasing curing time led to a porosity reduction and an increase in the cementation degree, which resulted in a denser structure and a greater strength of the specimens. Finally, the X-ray diffraction (XRD) and scanning electron microscope (SEM) results confirmed that hydrates increasingly filled the soil pores as the curing time increased, while increasing the heavy metal concentration hindered the development of hydrated reactions.