Hydraulic conductivity determination of compacted sand-bentonite mixture using filter press
RAZAKAMANANTSOA ; BARAST ; DJERAN-MAIGRE
Type de document
ARTICLE A COMITE DE LECTURE REPERTORIE DANS BDI (ACL)
Langue
anglais
Auteur
RAZAKAMANANTSOA ; BARAST ; DJERAN-MAIGRE
Résumé / Abstract
This paper presents a method to adapt a measurement in order to enhance its exploitation time and provide a suitable comparison with standard permeability tests. The filter press apparatus used for the fluid loss test (FLT) was selected to elaborate a hydraulic performance method, which is used for compacted sand-bentonite mixtures. An analytical method was developed for hydraulic conductivity determination.
Material and test parameters (hydraulic pressure Po, hydraulic gradient i, hydraulic conductivity ko, and coefficient) were highlighted. Series of experiments were performed with a filter press and rigid wall permeameter (RWP). The hydraulic study was performed on samples composed of soil with 2 %, 3.5%, and 5 % of an activated Ca-bentonite permeated with a weakly 110−3MNaCl. An improved FLT (IFLT) leads to a differentiation of the effect of clay concentration on hydraulic conductivity, but it is not suitable enough to estimate the hydraulic conductivity value as the RWP.
Direct test comparisons between RWP and IFLT show hydraulic conductivity values of the same order of magnitude. Sample compaction is known to reduce the void ratio variation. However, thickness variation may occur during testing due to a combination of swelling and consolidation effects caused by the hydraulic head. Then, the mechanical behaviour of the compacted sample was investigated with an oedometer. The IFLT method could provide rapid hydraulic performance indication compared to standard permeability tests. Further investigations would be needed to properly take into account the mechanical effect of the pressure.
Source
Geotechnical Testing Journal, num. 1, pp.9-18 p.
Editeur
AMERICAN SOCIETY FOR TESTING AND MATERIALS - ASTM
