Showing 5 results for Bentonite
Pakbaz M.c., Ahmadi C.,
Volume 1, Issue 2 (12-2003)
Abstract
This research include, more than 400 erosion tests performed on coarse and fine grain suspension materials. The purpose of tests was to determine erosion characteristics of mixtures of different materials. Samples of the .same constituents in different groups were cured tit two different setting time of // and 16 !tours before they were subjected to the constant hydraulic heads of 20 and 40 cm for ct time period of 30 urinates. The amount of erosion was measured as the weight loss of the samples offer the test. /n general the lower setting tune and the higher hydraulic head for a large group of samples showed higher erosion. For uniform sand samples when the cement content was 60-70 % the percentage of erosion (PE) was below 2. For the mixture of sand-cement, with the clay content below, 20% the percentage of erosion was below 2 and it increased to 15.5 for the clan, content of 58dc. Die addition of bentonite in the soil-cement mixtures in general did not affect the erosion.
M. Naderi,
Volume 3, Issue 1 (3-2005)
Abstract
Having observed the costly failures of different cutoff walls, that had been constructed
according to the mix design specified by reputable consultants in Iran, a research programme was
conducted to study the effects of constituent materials on the properties of plastic concrete. The
main properties, such as compressive strength, biaxial and triaxial strains, permeability, and
modulus of elasticity have been investigated using different mixes, obtained from prototype
production line plant, situated on site, because it was realized that the site production line and the
systems employed have major effects on the properties of plastic concrete. Statistical analysis of
the results, revealed the coefficients of influence of main constituent materials of plastic concrete
namely cement, bentonite, aggregate and water on its compressive strength and modulus of
elasticity. Having realized the cancelling effects of bentonite and aggregates on the measured
properties, some equations relating the quantities of cement and water to the compressive strength
and modulus of elasticity are introduced. Effects of clay and hydrated lime powder, as fillers were
also investigated leading to the proposal of limits for their safe and economic use. Since most of
the cutoff walls are buried structures, failure strains under both uniaxial and triaxial tests, with
values of cohesion and internal friction, are also presented in this paper.
Mohammad C. Pakbaz, M. Lorestani,
Volume 3, Issue 2 (6-2005)
Abstract
The main purpose of this research is evaluation of effect of chemicals on permeability of
sand- bentonite mixtures. The coefficients of permeability of sand- bentonite mixtures in water,
solutions of sodium and calcium chlorides, sodium hydroxide, acetic acid, methanol and carbon
tetrachloride were calculated using parameters obtained in 1- D consolidation test and Terzaghi’s
theory. At each void ratio permeability of samples in water is the lowest and that for carbon
tetrachloride is the highest. For all fluids the permeability index Ck is decreased as the percentage
of sand is increased. The largest Ck belongs to the samples tested in water and the smallest Ck
belongs to the samples tested in carbon tetrachloride.
N. Shariatmadari, S. Saeidijam,
Volume 10, Issue 2 (6-2012)
Abstract
Bentonite-sand mixture is one of the most important candidates for engineering buffer element in nuclear waste repositoriesso
the analysis of its thermo-hydro-mechanical behavior is important for design purposes.An innovative setup of classic oedometer
was used for swelling and compression study at high temperatures in this research. A fully calibration program was utilized to
include high temperature effects on measurements. This research shows that the elevation of temperature from 25 to 90◦C in
1:1bentonite-sand mixture in distilled water reduces free swelling potential and strain about 20 percent. The required time for
equalization of swelling is less in high temperature due to increasing in permeability. Also, the high temperature causes increasing
in compressibility rate and quantity for this buffer. For detection of this effect, XRD analysis showed that an increase in
temperature causes a decrease in basal spacing. So, the particles can come near to each other more than lower temperatures and
the amount of absorbed water in the microstructure of the clay is smaller.The effect of thermal history on behavior of bentonitesand
mixture has been showed and tried to clarify it. At similar stress-temperature states, thermal history causes different
deformation in samples. The highest temperature that bentonite has been experienced, controls its behavior in the next thermal
cycles.
M. Fadaee, M.k. Jafari, M. Kamalian, M. Moosavi, A. Shafiee,
Volume 11, Issue 2 (11-2013)
Abstract
During past earthquakes, many instances of building damage as a result of earthquake surface fault rupture have been observed.
The results of investigating a potential mitigation scheme are presented in this paper. Such plan provides a wall in the soil with
the aim of surface displacement localization in the narrow pre-determined location. This may reduce the risk of the future rupture
downstream the wall. To evaluate the efficiency of the method, this paper (i) provides validation through successful class “A”
predictions of 1g model tests for fault deviation by weak wall and (ii) conducts sensitivity analyses on fault position, fault offset
and wall shear strength. It is shown that wall can be designed to deviate rupture path even downstream of the wall can be
protected.
