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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