Oven-drying effects on the characterization of marine and lacustrine soils

¹ Priority Research Centre for Geotechnical Science and Engineering, University of Newcastle Australia, Newcastle, Australia
² Universidad de Los Andes, Bogotá, Colombia

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

Considering the extensive use of plasticity-based correlations in geotechnical practice to estimate soil parameters, the paper explores the influence of oven drying on the plasticity of two natural soft soil deposits: (i) Ballina clay, a marine structured soft clay from Australia and (ii) Bogotá clay, a lacustrine soft clay from Colombia. These two soils display extremely high plasticity when Atterberg limits are estimated using the natural soil. However, a strong reduction in liquid limit (up to 85%) is measured when the soil is oven dried before testing. The fact that the plastic limit seems insensitive to oven drying leads to a reduction in plasticity index close to 30% in Ballina clay and around 85% in the case of Bogotá clay. This behaviour is attributed to irreversible changes in soil fabric triggered by the oven drying process. The paper evaluates the consequences of neglecting oven drying effects in practice when adopting well-established relationships between mechanical parameters and soil plasticity. Plasticity-based estimates of index properties, compressibility and friction parameters are compared against values obtained from index tests as well as one-dimensional consolidation tests and ring shear tests.