Consolidation characteristics of a thermally cured sand–bentonite mixture

Abstract

Consolidation behavior of clays and sand–clay mixtures is an important topic in environmental geotechnics, thermal geostructures and disposal of hazardous wastes. The purpose of this paper is investigation of the changes in consolidation behavior of a sand–bentonite mixture due to the pre-curing at elevated temperatures. For this reason, 1:1 mixture of sand–bentonite was used to prepare samples 100 mm in diameter and 200 mm in height. The specimens were cured at 40, 60 and 80 °C for 1, 3 and 5 days under a constant confining pressure in a modified thermal triaxial cell. Then, consolidation behavior of the prepared samples which have been named as cured samples was investigated. The results show that the cured samples shifted from a reconstituted state to a quasi-structured one. A distinct yield stress was observed in compression curves of cured samples which was not apparent for reconstituted ones. The preconsolidation pressure of cured samples increased with increase in curing temperature and curing time. Also, the coefficient of consolidation and permeability increased as temperature increased, while both values decreased with an increase in curing time. Moreover, a number of specimens were tested under cyclic thermal paths which clearly proved change in behavior of cured samples to a structured one compared to the samples without thermal curing.