Duffield Associates operates two of the Mid-Atlantic region's largest privately owned materials testing laboratories, strategically located in our Wilmington, DE and Carlisle, PA offices. These extensive facilities combine a full range of testing equipment with isolated and conditioned environments required for precise test protocols.

Our full-service soils and concrete testing laboratories, complete with environmentally conditioned rooms for the storage and curing of concrete compression test cylinders, are accredited by the American Association of State Highway and Transportation Officials (AASHTO) and our Wilmington, Delaware lab is approved by the U.S. Army Corps of Engineers. Our geosynthetics testing laboratory has serviced solid waste industry clients for over 18 years.

Services include but are not limited to:

• Geosynthetics Conformance Testing
  Full range of typical QA/QC tests for Geomembranes, Geotextiles, Geonets, Geocomposites and GCLs along with welded seam Peel/Shear destructive testing.
  
  
• Geosynthetic / Soil Interface Shear Testing
  Interface friction angle and adhesion measured using 12" shear box and normal loads of 1- 100 psi. Soils / aggregates can be compacted in both upper and lower boxes, and tests completed in either dry or saturated conditions (shear box completely immersed in water).
  
  
• Soil Index Testing
  Tests include soil gradation, specific gravity, and plasticity, among others, which are used to classify soils and estimate their engineering properties.
  
  
• Consolidation Testing
  Provides a means of determining the time rate and potential magnitude of settlement of fine-grained saturated soils following stress application.
  
  
• Direct Shear and Triaxial Shear Testing
  Determines soil strength parameters including angle of internal friction and cohesion. Testing can be performed on undisturbed or remolded samples to simulate anticipated design stress conditions.
  
  
• Flex Wall and Rigid Wall Permeability Testing
  Measures permeability or hydraulic conductivity of granular or fine-grained water saturated soils.
  
  
• Concrete and Mortar Testing
  Determines the compressive strength of cementious materials including concrete, cement amended flyash, grout, and mortar.
  
  
• Proctor Testing
  Determines the maximum dry density and optimum moisture of soils utilized in construction.