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.
- View the CPR guide.
- 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.
- Perform air content and slump testing at the point of placement.
- 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.
- Verify all the information printed on the Certificate of Compliance is correct:
- 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.