Study on the strength, leachability, and electrical resistivity of lead-contaminated soil solidified with a slag-based binder

Solidification/stabilization (S/S) is the main method for the remediation of heavy metal–contaminated sites, and strength and leachability are common indicators for evaluating S/S efficacy. However, acquisition of strength and leaching parameters of solidified soil is time-consuming and expensive. There is a need to seek indirect measurements of these parameters for the evaluation. A slag-based binder composed of ground granulated blast furnace slag (GGBS), quicklime, and phosphogypsum was developed to solidify/stabilize lead-contaminated soil. A series of tests were conducted to investigate the influences of curing time and initial Pb concentration on unconfined compressive strength (UCS), leachability, and electrical resistivity of solidified soil. The relationships between electrical resistivity and UCS and leached Pb concentration were discussed in terms of linear, exponential, and logarithmic regression to seek a new indirect measurement. It was observed that UCS and electrical resistivity of solidified soil increased substantially with the curing time and decreased significantly with the initial Pb concentration. Correspondingly, the leached Pb concentration decreased substantially with the curing time and increased with the initial Pb concentration. The electrical resistivity of solidified soil had an obvious positive correlation with UCS and a negative correlation with leached Pb concentration, indicating that S/S efficacy can be indirectly evaluated by electrical resistivity. The research results are helpful for the remediation and evaluation of heavy metal-contaminated soil.