Maintenance & Rehabilitation. Treatments. Crack Sealing. Sealant Types. Asphalt Pavement Preservation: Identification of Alternative Treatments

Transcription

1 Asphalt Pavement Preservation: Evaluation, Maintenance & Rehabilitation Maintenance & Rehabilitation Treatments Identification of Alternative Treatments Before selecting a treatment for a pavement, we need to have a working knowledge of the various treatments We also need to know the proper time to apply a treatment in order to obtain the most economy and effectiveness Potential Treatments for HMA Pavement Rehabilitation Sealing Patching (Localized Repair) Cold Milling Surface Rehabilitation Techniques HMA Overlays PCC Overlays Recycling/Restoration Maintenance & Rehabilitation Treatments Sealing Reasons for Sealing sealing is applied to Preserve the intended design life of the pavement Extend the service life of the existing HMA by reducing moisture infiltration Prepare the existing pavement prior to construction of an HMA overlay Sealant Types Thermoplastic sealant materials common for HMA application Liquefied sealant materials for HMA application Thermosetting sealant materials not commonly applied to HMA pavements Used for PCC pavements 1

2 ODOT 423 Sealing, Hot Applied Type I, ASTM D 6690, Type II (D 3405) Type II, PG 64-22, 5% Polyester Fibers Type III, PG 64-22, 7% Polypropylene Fibers Type IV, Prepackaged w/ 2% Polyester Fibers meeting properties of Type II Sealant/ Filler Table Purpose and Application Reduce moisture infiltration Cause of stripping, cupping, delamination Reduce incompressible materials intruding into cracks Thermoplastic & liquefied sealants are applicable to HMA pavement Limitations and Effectiveness Continuing debate regarding the cost effectiveness of crack sealing SHRP experiments SPS-3 examined the effect of sealing activities on pavement performance sealing performed well except in dry regions of U.S. Limitations and Effectiveness General consensus among states that supports sealing cracks as a cost effective rehabilitation or maintenance treatment 66% of States seal cracks in HMA pavements Treatment Considerations Climate conditions Highway classification Traffic level and % trucks Pavement condition and planned rehabilitation characteristics s and placement configuration Procedures, equipment, and safety 2

3 Proper Treatment at Proper Time Types of Treatment Sealing the crack at this time will prevent having to patch at this time. Two different procedures have been defined in the Manual of Practice, SHRP-H-348 and adopted by FHWA sealing filling Sealing The placement of specialized materials either above or into working cracks using unique configurations to prevent the intrusion of water and incompressibles into the crack Working crack has horizontal and/or vertical movement 0.1 inch annually Filling The placement of materials into nonworking cracks to substantially reduce infiltration of water and to reinforce the adjacent pavement Nonworking crack has movement < 0.1 inch annually Differences in Treatments Based on the previous definitions Objectives of crack sealing are significantly more difficult to accomplish than those of crack filling sealing requires Greater costs Use of specially formulated materials Considerably more forethought & planning More sophisticated equipment Factors Affecting Performance Pavement condition before treatment Type of sealant Configuration of treatment Preparation of crack Application temperature & method Quality control Weather conditions 3

4 Ideal Application Conditions Placement Configurations Surface in good condition Good base support Little or no secondary cracking Little or no raveling at crack face Cool weather (fall or spring) Proper preparation (clean and dry) Simple Flush Fill Standard Reservoir And Flush Reservoir Placement Configurations Placement Configurations Simple Band-Aid Band-Aid Standard Recessed Band-Aid Band-Aid Standard Reservoir And Recess Recess Capped Cap Reservoir Reservoir Placement Configurations Deep Reservoirand-Recess Backer Rod Shallow Recessed Band-Aid Band-Aid Reservoir Cost Considerations Amount of cracks to be filled or sealed Type of crack filler / sealer costs: $0.05 to $3.75 per lb. Equipment and personnel required Estimated performance of crack fill or seal Method of payment linear feet of cracks, square yards or pounds of sealant Installed cost: $1.00 to $5.00+/m ($0.30 to $1.50+/ft.) 4

5 Construction Sequence sealing refacing (routing) cleaning Sealant installation filling cleaning Sealant installation Rotary Impact Router & Sawing Routing & Cutting and Joint Sawing Airblasting Hot Compressed Air Lance & Plowing Jts. Plowing Concrete Joints Cleaning s and Joints Saw Cut & Cleaned Squeegeed Sealant Cut and Cleaned 5

6 Finished Seal Finished Seal Filling Sealed Sealing Prior to Surface Treatments or Thin Overlays Ideally plan sealing program 1-yr ahead of Surface Treatment or Overlay Do not leave an over-band thickness of more than 3/16. Rural vs. Urban Traffic Control Tracking Contractor Solutions for Tracking Wetting 1% UP 70 5%, 30-mesh crumb rubber (0.17) Glenzoil for small areas such as Intersections Sand Maintenance & Rehabilitation Treatments Patching With Asphalt Mixtures 6

7 Reasons for Patching Patching Applications Patching the existing HMA pavement with asphalt materials Extends the service life of the existing HMA Improves ride on pavement Improves traffic flow & safety Prepares existing pavement prior to construction of an HMA overlay Moderate Severity High Severity Descriptions Asphalt Patching s Hot mix asphalt (HMA) Placed immediately while hot Standard dense graded HMA Proprietary mix Cold mix with modified emulsion binder Proprietary admixtures used Descriptions Asphalt Patching s Cold mix Often used as temporary patches Placed in stockpile and used over a period of time (emulsion or cutback asphalt) Special open-graded mixes Limitations Patching may not be appropriate for all applications Temporary patches have short life Pavement structure may be inadequate Principal problem may not be corrected Not cost-effective when pavement is extensively deteriorated Asphalt patching is not recommended for permanent repair of rigid pavements Effectiveness Full-depth HMA patches normally provide the maximum patching effectiveness Many proprietary patching mixtures have been found to be very effective Cold mix is useful when hot mix is not available & if proprietary mix is too expensive 7

8 Too Many Potholes Too Much Pothole Performance Winter Patching Conditions Winter maintenance Throw and Roll the most cost effective Spray injection device also very efficient Summer maintenance Semi-permanent patch often best Pennsylvania found it to be 3 times more cost effective on LCCA basis Throw and Roll Remove water/snow from pothole Fill pothole with patching material Compact patch using truck tires Verify that compacted patch has some crown (between 3 and 6 mm) Move on to next pothole Open repaired section to traffic as soon as maint workers & equipment are clear Automated Patching Equipment Spray injection procedures Blow debris from hole Spray hole with binder for tack coat Blow aggregate and binder into hole Top off with a layer of uncoated aggregate to prevent tracking May be rolled to improve smoothness 8

9 Automated Patching Equipment Semi-Permanent Patch (Full-Depth HMA) Mark boundaries of patch Cut boundaries of area to be patched Clean and repair foundation Apply tack coat Fill the hole with patching material Compact the patch Clean up Full-Depth HMA Patch What s Wrong Here? And Here? What s Wrong Here? Maintenance & Rehabilitation Treatments THE END Questions? Comments? 9