GEOTECHNICAL & ENVIRONMENTAL SOLUTIONS

Contaminated Testing

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Contaminated Testing

Our triaxial permeability and triaxial strength setups have the capability to perform Contaminated and Non-Contaminated tests. Many different proposed research methods and standards may be used, or alternatively, we can customize the test method to suit our clients’ requirements with respect to soil strength, pore water extraction with applied confining pressures, permeability flow rate and chemical composition of liquid outflow.

Conventionally, engineering characteristics of soils (e.g., shear strength, permeability, etc.) are tested without considering the influences of the in-situ environments. One of the factors that can affect soils’ engineering behaviors is the chemical composition of the soil pore water or the groundwater. Researchers and engineering practices have been indicating that soils, especially clayey soils, can show very different strength and permeation characters while exposed to liquids with high chemical concentrations. Those liquids are commonly observed in landfills, tailing dams, coastline groundwaters, and industrial sites.

Similar conclusions can be made for stabilized soils as well. In modern civil engineering or road engineering, the stabilization of soft or swelling clays using lime, cement, or other cementitious materials is widely adopted. However, most of the tests that are used to generate design indices, neglect the potential influences of the internal and external chemistry environments by using (a) short-term test schemes, and (b) tap water or distilled water. Meanwhile, in the real world, pH environment changes and attack of leachates (sea water intrusion in the coastal highway for example), may all pose a great danger on the strength and durability characters of those stabilized materials. 

 

Contaminated Permeability Tests

For Contaminated Triaxial Permeability tests, two special toxic interface units are required and usually chemical equilibrium needs to be achieved before the termination of the test. Chemical composition of the inflow and outflow is constantly monitored during the test. The outflow liquid is collected and sent to analytical chemistry laboratories for analysis.

Generally, contaminated triaxial permeability tests come under 3 main procedures:

  1. Permeability characters when the sample has been contaminated already. The permeant can be clean or contaminated liquid.
  2. Permeability characters when the sample is uncontaminated. The permeant can be contaminated liquid.
  3. Permeability characters when there is a high possibility that the sample will be contaminated by leachates in the near future, e.g, sample is first saturated with clean liquid and then subjected to contaminated liquid permeation.

 

Contaminated Strength Tests

Our equipment for strength and compressibility of soils are also compatible with the contaminated liquid. Therefore, the client is provided with options to test their samples with considerations of site water or contaminated water. Those tests include but are not limited to:

  1. Triaxial strength characters when the sample is saturated by contaminated liquid.
  2. The swell and collapse characters of soil sample or clay based geosynthetic materials when inundated by contaminated liquid.
  3. The consolidation characters of soil sample or clay based geosynthetic materials when inundated by contaminated liquid.

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