Base Stabilization

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Primary Resource

The inspector plays a vital role on every construction project ensuring that the completed operations comply with the plans and specifications. Base stabilization is similar to FDR; therefore, ARRA's Basic Asphalt Recycling Manual (BARM) and their best practice guidelines for FDR, along with the documents listed under Additional Resources should be consulted as guides.. 

Inspection Guidelines

With base stabilization, like most paving projects, the primary goal is to produce a strong, durable base course that is ready to receive a wearing surface. Inspectors can help achieve this goal by ensuring that the process is in accordance with the contract documents as follows: 

Mix Design: Verify representative samples were obtained throughout the project and that a mix design(s) was performed by a qualified lab resulting in a mixture that meets or exceeds the contract documents.

Surface Preparation: Walk or drive the entire pavement section to recieve the stabilized base for the day to ensure the surface has been properly prepared and that all pre-construction repairs have been performed. 

Acceptable Weather: Measure the air temperature and check conditions for anticipated heavy rainfall and freezing weather to determine if construction can start/continue.

Traffic Control: Verify that the proper traffic control is in place to keep the traveling public safe during construction.

Quality Equipment:

  • Verify that the stabilizing agent system of the central plant mixer is equipped with a meter capable of recording the rate of flow and total amount of each liquid added to the stabilized base material
  • Check the stabilized mixture for uniformity and homogeneity as it is discharged from the central plant mixer
  • Verify that the haul trucks are of the required type, size, number and that tarps are working properly
  • Verify that the on-board stabilizing agent/additive system of the reclaimer is equipped with a meter capable of recording the rate of flow and total amount of each liquid being added to the stabilized material.
  • Verify that nozzles and spray bars of the reclaimer or central plant mixer are working properly and are not plugged.
  • Verify that the bulk spreader is properly calibrated and is capable of accurately dispensing the required quantity of dry stabilizing agent/additive.
  • Verify that motor graders used have cross slope indicators and are in accordance with the contract documents.
  • Verify that the reclaimer is properly mixing the material.
  • For foamed asphalt, verify that the proper half-life and expansion ratio is being maintained.
  • Verify that the compaction equipment is of the required type, number and size and that scrapers and spray bars are properly working.

 Quality Workmanship:

  • Verify that the stabilizing agent is being properly mixed.
  • Verify that the mixing of water and stabilizing agent is adequate to ensure a homogenous, consistent blend throughout the treatment section.
  • Monitor the amount of water introduced to maintain the specified range of optimum moisture content.
  • Verify that the stabilized mixture is placed to the proper depth, grade and cross-slope. 
  • Check that longitudinal and transverse joints are properly constructed.
  • For cementitious stabilizing agents, verify that maximum mixing and compaction time frames are maintained.
  • Verify that a control strip was established to determine the compaction procedures.
  • Verify that the rolling procedure established in the control strip is followed and that the compacted density is within the specified range. 
  • Verify that the completed section is trimmed to the proper grade and cross-slope.

Application Rates: Periodic checks should be made to verify that the amount of material being added to the stabilized base mixture is within allowable tolerances.


  • Verify that the stabilized mixture can support the anticipated loads and will not impair material curing before opening the stabilized base section to light traffic.
  • Verify that the completed stabilized base mixture is properly cured.

Additional Resources

  1. Guide to Full-Depth Reclamation (FDR) with Cement. National Concrete Pavement Technology Center, Institution for Transportation, Iowa State University, Portland Cement Association, March 2017.
  2. Soil Stabilization for Pavements Mobilization Construction. EM 1110-3-137, US Army Corps of Engineers, April 1984.
  3. Lime-Treated Soil Construction Manual, Lime Stabilization & Lime Modification. Bulletin 326, National Lime Association, January 2004.
  4. Soil Stabilization and Pavement Recycling with Self-Cementing Coal Fly Ash. American Coal Ash Association Educational Foundation, January 2008.
  5. Guide to Cement-Treated Base (CTB). EB236.01, Portland Cement Association.
  6. Soil-Cement Inspector's Manual. PA050.03, Portland Cement Association.
  7. Soil-Cement Construction Handbook. EB003.10, Portland Cement Association.