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Geotechnical
Laboratory Research Facilities
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Bender
Elements Setup (ASTM D 6758)
Peizo-ceramic elements (bender
elements) distort or bend when subjected to a change in volume. Two such
elements are placed opposite one another and inserted a small distance
into the soil sample (typically- 3 mm). The shear wave velocity is
determined with a known frequency controlled by the oscillator.
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Centrifuge (ASTM D 6527, D 425)
A centrifuge is so driven that a force equal
to 1000 times the force of gravity may be exerted on the center of gravity
of the soil specimen for 1 hour. However, the flexibility is retained in
defining the temperature, rpm and duration of centrifugation. commonly
used to determine the moisture equivalent of soil in the laboratory.
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Consolidation (ASTM D 2435)
A one dimensional consolidation setup with a
Distributed Data Acquisition System for data collection and test control
enables programmed consolidation process with reading and loading
schedules. Swell pressure can
be applied along the test and the loads either swap automatically or after
a prescribed amount of time defined by the user.
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Constant Rate of Strain (CRS) Equipment (ASTM D
4186)
Information concerning the rate and magnitude
of consolidation settlement of soil is essential in the design of earth
and earth supported structures. The equipment facilitates the
determination of rate of magnitude of consolidation when restrained
laterally and drained radially and subjected to controlled-strain loading.
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Curing Temperatures
Chemically stabilized soils cured at
different temperatures and the swell shrink behavior is monitored for a
period of time.
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Direct/Residual Shear (ASTM D 3080)
The determination of consolidated drained
shear strength of soil in direct shear at a controlled strain rate
enabling real time plots and automatic data acquisition system with a
flexibility of defining three normal loads simultaneously. The UU shear
strength can also be determined controlling the necessary valves.
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Consolidation/Pressure Swell Frames
(ASTM D 2435)
The test is commonly used for undisturbed
fine grained soil specimens and is also applicable to stabilized and
compacted soils. the test enables to perform constant load increment
duration of 24 hrs and successive increments there of. Time-deformation
readings are noted to calculate the Cc and Cα
manually.
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Humifier
(ref ASTM D 2974)
The apparatus is used for evaporation of
total moisture at room temperature (air drying) generally adopted for
determination of moisture content, ash content and organic matter in
peats, organic clays such as mucks and organic silts. This method provides
a more stable sample for determination of pH, cation exchange and nitrogen
content.
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Moisture Room
The temperature controlled ambience is
maintained for storing samples with out any loss of moisture and testing
specifications to ensure the repeatability of test results.
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Constant Head and Falling
Head Permeameter (ASTM D 5084, D 4630)
The High Pressure Permeameter is best suited
for clays and stabilized soils as they need longer saturation periods. The
permeameter heads and tube are made so that high pressure as well as
standard low pressure permeability studies may be performed. The unit is
capable of maintaining a pressure of 60 psi (400 kPa) and can be used both
for constant head and falling head permeability.
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Pneumatic Consolidation
(ASTM D 2435)
The Pneumatic Consolidation Apparatus for
stress controlled consolidation testing is equipped with a pneumatic load
frame designed to apply loads instantaneously and to maintain any set
load, regardless of sample compression occurring within the loading
interval. Compatible for three load ranges, the load frame uses a
dual-piston system for handling loads to 16 or 32 tsf while retaining
sensitivity in the lower load ranges.
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Bar Pressure/Ceramic
Extractor Plate for Suction measurements
Suction is one
of the most important parameters describing the moisture condition of
unsaturated soils.
In the calibration process with pressure
plates, the filter papers are either directly put on the porous disks or
embedded in soil specimens on the porous disks.
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Pulverizer
Used for crushing the soil for some
specific tests which require the fines portion to meet the standard
testing conditions.
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Resonant Column Device
(ASTM D 4015)
A non destructive method (with in strain
amplitude of 10-4 rad) to evaluate the shear modulus, shear damping for a
solid cylindrical specimen under undisturbed and remolded states. The
vibrator and the soil specimen can be enclosed in a triaxial chamber to
apply all-around pressure and axial load.
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Cyclic/Repeated Load Triaxial Setup
(ASTM D 3999)
The equipment enables the determination of
modulus and damping properties of soils in either undisturbed or
reconstituted phase by either load or stroke controlled cyclic triaxial
techniques. Resilient Modulus for subgrade soils can be calculated subjecting
the sample to a loading pulse of 0.1 sec duration and unloading of 0.9
sec. Supports AASHTO-TP 46 (base/subgrade soils) and AASHTO T 307.
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Sample Extruders
To extrude the specimen after compaction, the
extruders shown adjacent are for the cylindrical soil specimens of smaller
diameter.
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Soluble Sulphates Studies
The testing lab enables artificial synthesis
of Ettringite and soluble sulphates analysis using gravimetric method to
understand possible heaving mechanisms. In the current NSF research
project at UTA, the soil specimens will be mixed with sodium sulfate in
order to synthesize the desired sulfate level before treated with cement
and lime (treated soils) and without any chemicals (raw soils).
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Torsional
Ring Shear Test (ASTM D 6467)
This test method provides a
procedure for performing a torsional ring shear test under a drained
condition to determine the residual shear strength of cohesive soils. This
test method is performed by deforming a presheared, remolded specimen at a
controlled displacement rate until the constant minimum drained shear
resistance is offered on a single shear plane determined by the
configuration of the apparatus.
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Triaxial Setup 1
(ASTM 4767, D 2850)
The shear strength properties of a soil are
critical for calculations involving foundations and earth embankments.
This test covers the determination of strength and stress-strain
relationship of a cylindrical soil specimen consolidated isotropically and
sheared in either drained or undrained conditions till the limiting strain
value has been reached. The test enables the UU, CU and CD tests on the
specimen with DAS.
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Triaxial Setup 2
The shear strength properties of a soil
are critical for calculations involving foundations and earth embankments.
This test covers the determination of strength and stress-strain
relationship of a cylindrical soil specimen consolidated isotropically and
sheared in either drained or undrained conditions till the limiting strain
value has been reached. The test enables the UU, CU and CD tests on the
specimen with DAS.
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UCS Setup
(ASTM D 2166)
This test methods determines the unconfined
compressive strength of cohesive soil in undisturbed, remolded or
compacted state. mostly applicable for soils which do not bleed or
expel water and retain their intrinsic strength after removal of axial
loads. three normal loads are applied to determine the failure envelope of
the soil.
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