Osmotic consolidation of expansive soil

Abstract

The mechanical behavior of expansive soils is influenced by the concentration of salts in their pore water. Research has shown that volume change of soil can occur due to a difference in salt concentration in the pore water between different zones of the soil as a result of either osmotically-induced consolidation or osmotic consolidation. The effect of the salt concentration of the pore water in unsaturated soil mechanics can be expressed as osmotic suction. Very little work has been done to quantify the mechanical equivalence of osmotically-induced and osmotic consolidation. This study attempts to quantify the mechanical stress equivalence of consolidation of an expansive soil submerged in a salt solution. Two remoulded soil samples of kaolin-bentonite mixture in proportions of 70%-30% and 90%-10%, (kaolin-bentonite) by dry mass were submerged in different concentrated salt solutions to investigate the effect of osmotic suction. Results showed that osmotic suction caused an additional settlement over the consolidation settlement under a mechanical stress but does not affect the soil compressibility. The osmotic coefficient of volume change (mπ) is only a fraction of the coefficient of volume change (mv). .

Study on Osmotic Consolidation and Hydraulic Conductivity Behavior of an Expansive Soil Inundated with Sodium Chloride Solution

“…Various researchers have investigated the structure of compacted clay using scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) tests in order to incorporate the double structure at the microstructural and macrostructural levels [29][30][31][32][33][34][35][36][37]. Silicate clays are blended in a defnite proportion of one aluminium or magnesium octahedral sheet sandwiched between two silica tetrahedral sheets.…”

Volume change in compacted claystone-bentonite mixtures as affected by the swamp acidic water

“…The volume change occurred in the sample was due to the difference in the concentration of cations in the pore water and the acidic water. This process is known as osmoticallyinduced consolidation or osmotic consolidation [40,41]. The high concentration of cations in the acidic water (table 1) results in the outward flow from within to balance these conditions.…”

Osmotic Oedometer Using Sodium Chloride Solution and Reverse Osmosis Membrane

“…The osmotic technique was developed by biologists (Lagerwerff, Ogata, and Eagle 1961) and introduced to soil science by Zur (1966) and geotechnical engineering by Kassiff and Shalom (1971). The osmotic technique should not be confused with osmotically induced or osmotic consolidation (Barbour and Fredlund 1989;Bulolo and Leong 2019) wherein salt solution replaces the pore water in a saturated soil specimen, causing volume change. An osmotically induced or osmotic consolidation test is usually conducted in an oedometer without the use of a semipermeable membrane (e.g., Di Maio 1996).…”