Concrete Pavement Rehabilitation

  • Review the following:
    • CPR Standards Details, 2302 Standard specification (Spec book), Special Provisions, Plans, and Schedule of Materials Control (SMC.)  If needed, Contact the MnDOT Concrete Engineering Unit for clarification.  
    • Attend the pre-construction meeting if possible.
  • Marking Repairs:
    • Have Contractor set up a lane closure at least 1 day in advance of beginning CPR work. 
    • Check soundness of concrete pavement with hammer, sand, and/or chain drag.
    • Use paint to mark the areas that require repair work.
  • Pavement Removal:
    • Ensure the erosion control devices are in place before any concrete sawing commences.  
    • The pavement needs to be swept with a pickup broom on a regular basis.
  •  Verify all materials are certified and approved. 
    • Check the approved products lists on the Approved/Qualified Products website. 
  • Partial Depth Repairs (Type B):
    • Check all Type B repairs to make sure the deteriorated concrete is removed.
    •  Check repairs are sandblasted clean and are clear of laitance and oils.
    • Assure the bonding grout does not whiten (dries) after application in Type B repairs. If the bonding grout whitens reject the repair and re-sandblasting of the repair.  
    • Before concrete placement, ensure the compression relief material (joint filler) and / or joint reestablishment material (wax coated cardboard) is in place.  
    • To prevent reflective cracking, place joint filler between the repair and the adjacent lane.
    • If needed perform gradation tests on the 3U18 aggregate.
  • Full Depth Repairs (Type C):
    • Verify the base is level with the bottom of the pavement and compacted.  Additions to / removal of in place base material is common.
    • Check for proper installation of dowel bars by requiring an adhesive anchoring test section. 
    • The specification requires the installation dowel bars and then cores are taken in order to check the adequacy of the adhesive surrounding dowel bars.
  • Dowel Bar Retrofit (DBR):
    • Make sure the bottoms of the slots are flat and sandblasted clean.
    • Ensure the crack / joint caulked completely.  If the DBR backfill material infiltrates into the crack / joint a compression spalls will likely occur.
  • Placement and Finishing:
    • Ensure proper consolidation (vibration) of the concrete.
    • Refer to the specification for straightedge tolerances.  Check the repairs as often as necessary to ensure smoothness.
    • It is good practice to finish Type B repairs from the middle of the repair to the outside of the repair.
  • Curing:
    • Review current curing requirements.
    • Verify an approved curing compound is used from the Approved/Qualified Products website.
    • Check application rate of curing compound for uniformity, yield, and timely placement. 
    • Ensure compliance with rain and cold weather protection requirements.
  • Perform all required sampling and testing in accordance with Schedule of Materials Control.
    • When the concrete is not pumped, perform air content and slump testing at the point of placement. If the concrete is pumped, take sample at the point of delivery.
    • If there is any question about the consistency or the quality of the concrete, run additional tests as necessary.
    •   Notify Contractor and truck driver if air content or slump results are outside of Specifications.
  • Compressive Strength Testing (Cylinders):
    • Check the Schedule of Materials Control for sampling rates.
    • Make and store cylinders where they are protected from vibration or disturbance until placed in the curing tank.
    • Provide protection from extreme variations in temperature from the time of casting cylinder until it is transported to the lab.
    • Make additional control cylinders as necessary.  Cure control cylinders in the same manner as the repair.
  • Collect and initial all Certificate of Compliances (Batch Tickets): 
    • Verify all the information printed on the Certificate of Compliance is correct:
      • Verify S.P. Number
      • Verify Mix Number
      • Verify delivery time is within Specifications
      • Verify Water – Total Actual Water vs. Mix Design Water
      • Verify whether or not water is allowed to be added
      • Record any additional water that was added at the job site.
      • Verify Mn/DOT Certified Plant I Technician representing the Producer signed the first Certificate of Compliance for each mix type, each day.
  • Check repairs for failures: 
    • All CPR repairs have a warranty period, it is essential the repairs are checked for failures before the warranty time period expires.
  • Maintain daily diary:
    • Includes hours, equipment, concrete temperatures, air content, slump reading, cylinder data, stations paved, width, depth, yield, weather, air temperatures, and problems or unique circumstances encountered.
  • Field Documentation:
    • Document all 3U18 field test results in the CPR Workbook
    • Submit both to the Concrete Engineering Unit on a weekly basis

References:   Mn/DOT Standard Specifications for Construction, Contract Plans and Special Provisions, Schedule of Materials Control and Mn/DOT Concrete Manual.