CONCRETE PAVING INSPECTION

Review Contract and Plans:

Obtain plans and special provisions and study them in detail.
Attend the pre-construction meeting.
Attend the pre-paving meeting.

Determine Random Testing Locations:

Determine random testing locations using the Thickness, Texture and MIT-SCAN Workbook.

Become familiar with concrete paving equipment and paving operations.

Check paving equipment for proper adjustment and compliance with specifications.
Understand the function of each piece of equipment.
Become familiar with paving sequence and review field controls for line and grade.
Verify string line is set sufficiently in advance to avoid delays.
Check vibration equipment and verify vibration monitors are operating correctly.
Verify that utility work and conduits are complete. Pre-locate utility fixtures to be incorporated into the pavement.

Placement on Grade:

Check that the grade is in a moist condition ahead of the concrete placement.
Ensure the trucks hauling concrete do not cause grade displacement or damage.

Placement on Asphalt or Asphalt Bond Breaker:

Clean the milled surface by sweeping and patching, or as directed by the Engineer.
Maintain the asphalt surface in a moist condition and at a surface temperature not greater than 120 °F before or during concrete placement.
Ensure the trucks don’t tear up the asphalt during turning movements by using plywood or similar material.

Placement on Geotextile:

Clean the surface of the concrete prior to placing the geotextile fabric by power sweeping and air blasting.
Ensure fabric is tight without excess wrinkles or folds.
Maintain the surface in a slightly damp, not saturated, condition before placing the concrete.
Remove excess water by use of rollers or method approved by the Engineer.
Ensure the Contractor trucks don’t tear up the geotextile during turning movements.

Reinforcing Steel Placement:

Check size, length, spacing, and placement of reinforcing steel, and any other special reinforced panels.
Verify proper reinforcement size, grade, lap ties, depth and spacing.
Check if the required mechanical placer is placing it at the proper depth.
Ensure location at proper elevation.
Make sure bars are the right size and length, and properly spaced.
Make sure tie steel is not placed at a doweled joint.
Verify supplemental steel is placed over new culvert and pipe per the Standard Plate.
Ensure reinforcement steel is placed at manholes, gore areas, permanent headers, ends of longitudinal joints terminating at a contraction joint, etc.

Dowel Basket Assemblies:

Check proper size and type of dowel bar assembly.
Review the required Quality Control Plan for Anchoring Dowel Basket Assemblies.
Observe for approval the Contractor’s fastening method for dowel bar assemblies before the beginning of concrete placement and each day prior to beginning paving.
Check dowel bar assemblies for proper placement to assure that they are parallel with the base and centerline of road, properly supported and staked.
Make sure dowel baskets are securely anchored on the bottom rail using the correct number of anchors. Refer to the Standard Plates for details.
If a bond breaker layer is used, make sure dowel baskets are securely fastened through the bond breaker layer into the concrete below.
Check the placement of dowel assemblies at catch basins and manholes; keep joint at least 3 ft from structure.
Make sure an approved bond breaker material has been applied to dowel bars.
Confirm joint sawing locations are marked at the same location as the dowel baskets.
Mutually use the MIT-SCAN T2 device for locating dowel basket assemblies in the plastic concrete.

Verify the Contractor’s prepared for inclement weather (rain or cold weather conditions).

Review the Contractor’s written cold weather protection plan.

Slipform Construction:

Ensure the pavement is placed before placing the curb and gutter. If the sequence of operations includes placing the curb and gutter before the concrete pavement, the Contractor must submit a jointing plan for approval prior to placing the curb and gutter.
Check string elevations verses what is staked.
Check line is directly above tack reference hub.
Check string tension by looking for sags in the line.
Verify calculated pavement thicknesses using Contractor’s grade and line control string lines.

Fixed Form Construction:

Inspect pavement forms to ensure cleanliness and compliance with form requirements and characteristics.
Verify the forms are set to the alignment and grade shown on the plans.
Use tape measure to check for alignment from offset tack line and visually inspect for final alignment.
Use level to check for elevation from blue top to form line and visually inspect for final alignment.
Check forms for release agent coating.
When using keyway, verify the keyway is set at the proper height per the Standard Plans.
Verify the forms are not removed earlier than 12 hours after concrete placement unless otherwise approved.
Make sure the concrete is consolidated properly using hand-held or machine-mounted internal vibrators.

During Concrete Placement:

Make sure concrete is placed within the time specification.
If Ready-mix concrete is being used, collect, check, and initial the Certificate of Compliance.
Check that concrete is not lost on the haul road or sticking in the truck after it dumps.
When placing concrete adjacent to in-place concrete pavement, protect the existing transverse joints and the edges of the pavement.
Set manhole and catch basin frames or rings to the elevation shown on the plans during the paving operations.

Monitor paving operation for continuous placement and consolidation of concrete.

Make sure concrete is spread uniformly and ensure there is uniform strike-off.
Check to see that paver is not over or under loaded, and that concrete is “rolling” not “sliding” in front of the screed.
Check if vibrating tubes are operating
Spot check vibration equipment daily and verify vibration monitors are operating correctly.
Computerized vibration monitors are required on slipform pavers. Obtain an electronic copy of all vibration monitor data from the Contractor at the end of the project.

Concrete Appearance:

Check that the concrete is maintained at a uniform consistency.
Monitor the surface and edge slump.
Make sure the tamping bar is properly adjusted so large aggregate is tucked below the surface and not dragged.

Verify pavement dimensions:

Measure pavement width, thickness, crown, superelevation, edge slump, and joints match to ensure it meets plan requirements.
Observe the Contractor’s probing or scanning operations.
Spot check surface elevations of the concrete.
Check pavement surface using a straightedge to check for tolerance.

When Stringless Technology is used:

Check Contractor probing depths and pavement edge heights.
Pay attention to your daily quantities.
Spot check surface elevations of the concrete.
Verify control points are staked every 250 feet staggered or as requested.

Air Content and Slump Testing in accordance with the Schedule of Materials Control:

Observe the Contractor perform air content testing.
Perform correlation air content testing.
Air content test results should be recorded in the Air Content Workbook.
Require the Contractor test the slump if the concrete is suspected to be outside of required slump range.
Verify the air content and slump test results are within Specifications.

Flexural Strength Testing (Opening Pavement to Traffic):

Observe Contractor make beams.
Contractor removes beams from boxes, cleans boxes, and reassembles boxes.
Agency cures and breaks beams.
Record beam break results on Concrete Beam Test Data Workbook.
Verify minimum strength requirements have been met for opening pavement to construction and general traffic.
Cylinders are allowed to be substituted for beams.

Finishing:

Do not allow the Contractor to add water to the surface of the concrete to aid in finishing without the approval of the Engineer.
Check surface using a 10 ft straightedge to check for tolerance.

Texturing:

Ensure texturing is properly performed at the appropriate time
Check texture marks for uniformity.
Provide random sand patch test locations to the Contractor.
Verify texture by observing Contractor sand patch testing.
Contractor test results should be recorded on the Thickness, Texture and MIT-SCAN Workbook.
Review the Contractor’s concrete texture results for compliance.

Headers:

Construct construction headers and permanent headers as shown on the plans and Standard Plans.
Do not allow incorporating any concrete accumulated in the grout box of the paver into the pavement. Construct all headers such that the concrete contained in the grout box is removed from the project.
Use internal vibration to consolidate the concrete along header joints before final finishing.

Curing:

Verify an approved curing compound lot/batch is used by checking the Approved/Qualified Products list.
Visually inspect the curing compound. Sampling of the curing compound is not required unless the material appears defective.
Check application rate of curing compound for uniformity, yield, and timely placement.
Verify a uniform, solid, white, opaque coverage on exposed surfaces (equal to a white sheet of typing paper) at the time of application. If the curing compound has a base color (e.g., yellow), verify it is uniform, solid, opaque consistency.
Ensure compliance with cold weather protection requirements.

Sawing Joints:

Check joint sawing operation. Check joint location adjustments at side streets, inlets, manholes, etc.
Check appearance, depth, and width of sawed joints daily. No raveling and no random cracking should occur at the time of initial sawing.

Sealing Joints:

Verify joints are clean and dry before approving.
Do not allow traffic on the slab until the joints are sealed.

MIT-SCAN T2 Dowel Bar and Tie Bar Testing in Plastic Concrete:

Use the Thickness, Texture and MIT-SCAN Workbook to provide random testing locations to the Contractor
Observe the Contractor scan the tie bar steel and dowel bar anchoring.

Contractor test results should be recorded on the Thickness, Texture and MIT-SCAN Workbook.

Thickness Evaluation:

Use the Thickness, Texture and MIT-SCAN Workbook to provide random testing locations to the Contractor.
Determine if probing or scanning is required.
Verify the required plate size is used for probing and scanning.
Observe the Contractor’s probing, scanning and coring operation to verify authenticity.
Contractor test results should be recorded in the Thickness, Texture and MIT-SCAN Workbook.
Review the Contractor’s concrete probing and scanning results for compliance.
Collect and field measure the concrete cores immediately after coring.
Submit cores along with the completed Field Coring Report to the MnDOT Office of Materials and Road Research for official measurement and testing.

Pavement Surface Smoothness:

Make sure the Inertial Profiler is certified and displaying the certification sticker on each laser. Make sure Inertial Profiler operator is certified. See MnDOT Smoothness website for a list of the certified IP’s, required settings for individual certified Inertial Profiler’s, and certified operators.
Observe all Contractor profiling, unless approved by the Engineer.
Review the Contractor’s printouts containing the Inertial Profiler’s settings, each segment’s left and right IRI values, the signature of the operator and electronic PPF files submitted on the same day of the profiling.
Review the Smoothness Assurance analysis for contract compliance.
Determine if grinding is needed or required.
Check the final Concrete Profile Summary reports for contract compliance.

Maintain Agency Daily Diary:

Includes hours of production, equipment, concrete temperatures, air content, slump reading, cylinder and beam data, stations paved, width, depth, yield, weather, air temperatures, and problems or unique circumstances encountered.

Submit the following to the MnDOT Concrete Engineering Unit:

Air Content Workbook
Concrete Beam Test Data Workbook
Thickness, Texture and MIT-SCAN Workbook
W/C Ratio Calculation Workbook
JMF Concrete Aggregate Workbook (QC and QA)
Coarse Aggregate Quality Incentive/Disincentive Workbook
Concrete Profile Summary Worksheets