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Ask an expert: How does soil compaction testing add value to my project?

Geotechnical and Soil Compaction Testing Services in Iowa

Soil compaction is vital to the success of almost any construction project. Despite given design standards and specifications, the testing and verification of materials used in soil compaction can sometimes be overlooked or tested less frequently than desired. Using improper materials or methods during soil compaction can lead to foundation and slab cracks, soil erosion, utility pipe leakage/breaks, or trench settlement. It is important that the earthwork contractor and the materials testing agency communicate throughout the project to provide the best results for their client(s).

Soil compaction testing is often overlooked

Each lift of soil used for structural, site grading, or trench backfill should be tested to confirm that compaction requirements are met and material types being used are consistent with the geotechnical report.

Sometimes proper compaction is overlooked on projects where it actually is necessary. For example, a utility contractor may not think that the backfill for a water main trench needs to be tested because it appears to be in ‘green space’ far away from the new building structure. But, in reality, the material in the trench will support exterior pavement. If the material is placed without being tested by the testing agency, it may lead to cracking in the pavement.

However, soil compaction testing involves much more than determining if a specified soil compaction percentage is met or exceeded. In addition to recording the soil moisture and density, Braun Intertec technicians are trained to observe various factors. If any of the following factors cause delays or test failures, our licensed professional engineers may ask further questions to provide recommendations to the project team and keep the project moving.

What do our technicians and engineers consider when assessing soil compaction?

  • Material type – Is the material being compacted free of organics and debris? Is the correct Proctor being used or has the material changed? Are there any permeability concerns for this layer?
  • Lift thickness – Is the contractor placing soil layers in the lift thicknesses recommended by the geotechnical engineer? Has each lift been tested for moisture-density?
  • Moisture – Is the moisture content of the in-place soil within the specifications? Will weather events affect the soil layer after testing? Do the clayey soils need to be dried?
  • Methods of compaction – Does the equipment being used provide the correct type of compaction for this material (vibration, impact, pressure)? Do additional compactor passes improve the compaction test results? Is the subgrade below the new fill stable and provide a surface to compact against?

With these factors observed and evaluated by Braun Intertec technicians and engineers, you can be confident that the new soil fill placed beneath your building foundations, along your embankment, or under your pavement will be of the highest quality.

Learn more about soil compaction

If you would like to learn more about the science behind soil compaction. Click the button below to sign up for our webinar, “Soil Compaction Fundamentals: Understand the Science Behind Soil Testing”.

Ben Butler, PE Iowa Project Engineer

P: 319.365.0961