Electrical resistivity and strength properties of sodium hydroxide contaminated soil solidified with cement

Nine different contents of sodium hydroxide solutions, silt, and ordinary Portland cement were selected as basic materials to make the cemented soil blocks. The electrical resistivity under different current frequencies and unconfined compressive strengths were measured after curing for 3, 7, 14, 28, 60 and 90 days, respectively. The results show that the alternating current electrical resistivity decreases with the increase in current frequency for all content values. The higher the current frequency is, the smoother the electrical resistivity. The current frequency range of 5× 10⁴ to 10⁶ Hz is recommended to reduce the error resulting from the slight variation of current frequencies. The strength and electrical resistivity increase logarithmically with the increase in curing time. With the increase in content, the strength first increases linearly and then decreases linearly. The strength reaches the peak value at the content of 7.5 g x kg"^-1. The electrical resistivity decreases exponentially. A useful prediction formula for the strength is proposed, which was established according to the linear relationship between the strength and the electrical resistivity. Based on the influencing degree of sodium hydroxide on the strength of cemented soil, an evaluation standard for the electrical resistivity of cement-solidified sodium hydroxide-contaminated soil is also proposed.