Influence of water content on the electrical resistivity of biocemented soils investigated through the shape of the water retention curve and considering chemical effects

CERIS/IST, University of Lisbon, Av Rovisco País 1, 1049-001 Lisboa, Portugal

^* Corresponding author: rafaela.cardoso@tecnico.ulisboa.pt

Abstract

Non-destructive tests, such as geophysical electrical resistivity tests, can be useful to determine how Biocementation treatment in soils is distributed in volume. However, electrical resistivity is affected not only by void ratio but also by water content and the chemical nature of the pore fluid. This paper presents an experimental investigation performed to analyse the changes on the electrical resistivity of a sandy soil after biocementation treatment using enzymes, considering changes on water content. Electrical resistivity measurements were carried out using Wenner method and the water retention curves of the untreated and treated sands were measured using a Water Dewpoint Potentiometer (WP4). The water retention curves for the wetting paths were similar for both the treated and untreated soils, but suction measured during drying in the soil with biocement was higher than that of the untreated soil because of the chemical elements in the pore fluid and the presence of the biocement clogging soil pores. Electrical resistivity measurements do not allow to conclude to what extent the presence of biocement affects the conductivity of electricity through the soil, however electrical resistivity and soil suction are related even in the presence of the pore fluid ions due to the treatment. Detailed study of these parameters could help to understand if this non-destructive technique can be used to monitor biocementation progress in the volume of the treated soil.