On the intrusion of polyethylene glycol during osmotic tests

Tripathy, Snehasis; Tadza, Mohd Yuhyi Mohd; Thomas, Hywel Rhys

doi:10.1680/geolett.11.00016

Cited by 20 publications

(10 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Such response was observed for all tests with the CA membrane. This reflects an issue of stability of the membrane, a phenomenon pointed out by Tarantino and Mongiovi [3] and Tripathy and co-workers [8], among others.…”

Section: Testing Programmentioning

confidence: 80%

Response of different osmotic membranes and calibration of a coupled model capturing the temperature effect for the osmotic method

2016

View full text Add to dashboard Cite

Reliable suction control is of paramount importance for experimental unsaturated soil mechanics. The osmotic method, based on polyethylene glycol (PEG) and semi-permeable membranes, is one of the possible methods to control suction. Although this method is quite simple to implement, reliable results can only be obtained with adequate calibration curves linking suction and PEG concentration, and a good understanding of the factors influencing the method. Several studies have investigated different aspects of this method, including the osmotic potential generated by given PEG concentrations, but the effect of temperature is not yet fully captured. This paper presents the results of a comprehensive study of the osmotic method looking at the long-term response of three different types of membranes, the effect of temperature, PEG molecular weight (MW) and the combination of different MW cut off (MWCO) on the calibration curves. Finally the data were used to calibrate a model capturing the temperature effect, in a coupled manner, in order to provide a robust calibration.

show abstract

Section: Testing Programmentioning

confidence: 80%

Response of different osmotic membranes and calibration of a coupled model capturing the temperature effect for the osmotic method

2016

View full text Add to dashboard Cite

show abstract

“…The containers along with the specimens were placed in a temperature‐controlled bath (temperature = 20°C) during the entire testing period. Problems associated with an intrusion of PEG into soil specimens during osmotic tests, particularly at high applied suctions and in case of bentonite specimens, has been reported (Tripathy et al, 2011). The equilibrium time for the osmotic tests was 15 d, whereas a few months to about a year was required for suction equilibrium in the vapor equilibrium tests depending on the suction level and type of clay used.…”

Section: Methodsmentioning

confidence: 99%

Effective Stress in Clays of Various Mineralogy

Baille

Tripathy

Schanz

2014

Vadose Zone Journal

View full text Add to dashboard Cite

The effective stress in clays possessing a signiicant proportion of one of the clay minerals kaolinite, illite, or montmorillonite was determined based on the suction stress characteristic curves (SSCCs) of the clays. The SSCCs were determined based on the drying soil-water characteristic curves of the clays for a suction range of 0.03 to about 219.0 MPa. One-dimensional compressibility behavior of initially saturated clays was also studied by loading clay specimens up to a maximum vertical stress of 21.0 MPa. The effective stressvoid ratio responses of the clays during the drying process were compared with their saturated counterparts. The shapes of SSCCs and the magnitudes of minimum and maximum suction stress were strongly dependent on the mineralogy and the properties of the clays. For the clays with kaolinite and illite as the dominant clay minerals, the suction stress decreased, remained nearly constant, and then increased with an increase in the applied suction, whereas it decreased monotonically with increasing suction for the montmorillonite clay. A decrease in the suction stress caused an increase in the effective stress, which in turn reduced the volume of the clays. For applied suctions smaller than the air-entry value of any clay, equal magnitudes of suction stress and effective stress produced a similar volume change of the clay. The study clearly showed that suction changes beyond the air-entry value are less effective in producing volume changes in unsaturated soils, primarily because of a decrease in the effective stress due to an increase in the suction stress.

show abstract

“…Studiesin the past have shown disagreement between the test results from both vapour equilibrium and osmotic tests at higher applied suctions [15][10]. The differences were mainly attributed to alterations of the membrane pore sizes which enabled the crossing of PEG molecules into soil specimens [13]. The magnitude of the alteration was found to be significant for lower MWCO membranes.…”

Section: Suction-water Content Swccmentioning

confidence: 99%

“…One of the main drawbacks of the osmotic technique when using PEG 6000 along with molecular weight cut-off (MWCO) 3500 semipermeable membrane, is the intrusion of PEG solution into the soil specimen particularly at higher applied suction [13]. This problem occurs due to the breakage of the semipermeable membrane by soil fungi [14].…”

Section: Introductionmentioning

confidence: 99%

An Evaluation of Osmotic Technique Under Ultraviolet Germicidal Irradiation Exposure

Tadza¹

2017

GEOMATE

View full text Add to dashboard Cite

ABSTRACT:The osmotic technique, which uses polyethylene glycol (PEG) solutions of varying concentrations with semipermeable membranes of different molecular weight cutoffs (MWCO), is commonly used to apply suction in soils. Cellulose acetate membranes which are most commonly used, are susceptible to microbial attacks. This in turn will lead to the intrusion of PEG into soil specimens. Osmotic and vapour equilibrium techniques are often used to establish drying suction-water content soil-water characteristic curves (SWCC). In this study, suctions of 0.11 to 300 MPa were applied on Andrassy bentonite slurries. At higher applied suctions, the osmotic tests were carried under short length ultraviolet germicidal irradiation (UVGI). In addition, Atomic Force Microscopy (AFM) and Fourier Infrared (FTiR) were employed to evaluate the changes in the semipermeable membranes and PEG molecules, respectively. The water content of the clay obtained from the osmotic tests was found to be greater at the overlapping suction region. Interestingly, under UVGI exposure, the water content was found to be in good agreement with the water content determined using the osmotic technique at low suctions and the vapour equilibrium technique at higher suctions. FTiR spectrum and AFM results revealed that some changes had occurred on both the PEG and in the membrane pore sizes. However, these changes did not affect the final water content in the bentonite and therefore, more precise suction-water content SWCC for the clay could be established.

show abstract

On the intrusion of polyethylene glycol during osmotic tests

Cited by 20 publications

References 24 publications

Response of different osmotic membranes and calibration of a coupled model capturing the temperature effect for the osmotic method

Response of different osmotic membranes and calibration of a coupled model capturing the temperature effect for the osmotic method

Effective Stress in Clays of Various Mineralogy

An Evaluation of Osmotic Technique Under Ultraviolet Germicidal Irradiation Exposure

Contact Info

Product

Resources

About