Pavement Preservation Treatment Knowledge Transfer Analysis
The analysis discusses the peer exchange facilitators, knowledge transfer process between Lead and Explorer States, disadvantages of limited knowledge transfer, and details of pavement preservation treatment experience in various states. It emphasizes the importance of sharing expertise to enhance preservation efforts.
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Peer Exchange Facilitators: Larry Galehouse, P.E., P.S., National Center for Pavement Preservation Larry Scofield, P.E., International Grooving & Grinding Association (IGGA) Peer Exchange Sponsor: Antonio Nieves, Federal Highway Administration
A Lead State transfers knowledge - to Explorer State personnel. There would be 2 people from each of 10 Explorer States.
Disadvantages: Transferring knowledge to only 20 people (10 States) Where are the Lead States?
A Pavement Preservation Treatment Self Assessment Survey was initiated.
Rocky Mountain West Southeast 8 11 Alaska California Montana Nevada New Mexico Utah Washington Wyoming Alabama Arkansas Georgia Kentucky North Carolina South Carolina Oklahoma Tennessee Texas Virginia West Virginia
Midwestern Northeast 11 7 Illinois Indiana Iowa Kansas Manitoba Michigan Minnesota Missouri North Dakota Saskatchewan South Dakota Delaware Maine Maryland Massachusetts New York Rhode Island Vermont
States with Limited Treatment Experience & Knowledge Rocky Mtn. West 4 6 0 1 3 0 4 1 Southeast Midwestern Northeast Asphalt Treatment 8 11 11 7 6 7 2 10 0 1 10 6 6 8 0 9 2 0 9 5 2 5 4 3 1 2 7 4 Asphalt Rubber Chip Seals Cape Seals Chip Seals Cold In-Place Recycling Crack Filling Crack Sealing Flush Seals Fog Seals
States with Limited Treatment Experience & Knowledge Rocky Mtn. West 5 0 0 2 0 3 4 3 Southeast Midwestern Northeast Asphalt Treatment 8 11 11 7 8 1 0 3 1 5 6 5 9 3 2 3 3 10 6 4 3 0 3 6 0 5 2 3 Hot In-Place Recycling HMA/WMA Inlays (<2 ) HMA Patching Micro Surfacing Mill & HMA Overlay (<2 ) OGFC UTBWC Profile Milling
States with Limited Treatment Experience & Knowledge Rocky Mtn. West 5 7 5 4 3 6 Southeast Midwestern Northeast Asphalt Treatment 8 11 11 7 10 10 8 8 3 4 9 9 10 8 5 8 6 7 7 6 1 3 Rejuvenators Sand Seals Scrub Seals Slurry Seals Thin HMA (1 -1 ) Ultrathin HMA ( - )
States with Limited Treatment Experience & Knowledge Rocky Mtn. West 3 8 1 6 1 3 3 3 Southeast Midwestern Northeast Concrete Treatment 8 11 11 7 5 9 1 6 2 5 5 5 3 7 3 6 2 3 4 4 4 7 2 3 3 2 2 2 Crack Sealing Cross-Stitching Diamond Grinding Dowel Bar Retrofit Full Depth Repair Joint Sealing Partial Depth Repair Slab Replacement
States with Limited Treatment Experience & Knowledge Rocky Mtn. West 6 4 Southeast Midwestern Northeast Concrete Treatment 8 11 11 7 6 2 8 5 5 4 Slab Stabilization Spall Repair
a. Showcase selected treatments b. Ask agencies what topics to discuss in future peer exchanges a. Include as many agencies as the budget will allow
Mystic, CT Portland, OR Biloxi, MS Madison, WI
Requested Treatment Discussion at Peer Exchanges 1. Cape Seals 2. Cold In-place Recycling 3. Concrete Repair 4. Hot In-place Recycling 5. Hot Rubber Chip Seals 6. Inspection & Acceptance 7. Micro Surfacing 8. Scrub Seals 9. Slurry Seals 10. Thin Bonded Overlays
Requested Treatment Discussion at Peer Exchanges 1. Cape Seals 2. Cold Central Plant Recycling 3. Cold In-place Recycling 4. Hot In-place Recycling 5. Hot Rubber Chip Seals 6. Inspector Training 7. Micro Surfacing 8. Quality Assurance 9. SAMI s 10. Scrub Seals 11. Slurry Seals
Requested Treatment Discussion at Peer Exchanges 1. Cape Seals 2. Cold In-place Recycling 3. Concrete Repair 4. Hot In-place Recycling 5. Hot Rubber Chip Seals 6. Inspection & Acceptance 7. Micro Surfacing 8. Scrub Seals 9. Slurry Seals 10. Thin Bonded Overlays
Requested Treatment Discussion at Peer Exchanges 1. Chip Seals 2. Fog Seals 3. Hot In-place Recycling 4. Micro Surfacing 5. Rubber Chip Seals 6. Scrub Seals 7. Thin Bonded Overlays 8. Thin HMA Overlays 9. Ultra Thin Overlays
1. Offer State DOTs and local road agencies an opportunity to share good treatment practices. 2. Discuss pavement preservation lessons learned. 3. Increase interest in expanding treatment toolbox.
10 Peer Exchanges 37 State DOTs
Lexington, KY Sep 25-26, 2018 13 participants Concord, NH Oct 10-11, 2018 18 participants Dover, DE Nov 19-20, 2018 11 participants Bismarck, ND Dec 5, 2018 110 participants
26 participants Baton Rouge, LA Dec 11-12, 2018 54 participants Maplewood, MN Feb 27-28, 2019 21 participants Indianapolis, IN Apr 23-24, 2019
21 participants Portland OR Apr 30 May 1, 2019 Phoenix, AZ May 2-3, 2019 74 participants Macon, GA May 6-7, 2019 26 participants
Use of AR Chip Seals is found predominantly in New England and Southwest. The rubberized binder is made either by terminal blend or the wet process method. New England uses a PG 58-28 modified with15 - 20% tire rubber content. The 30 mesh rubber is sprayed at 0.5 - 0.6 gal/yd2 depending on pavement condition. Surface preparation is critical for a successful asphalt rubber chip seal. All pavement paint markings are ground off to prevent aggregate loss. Good weather conditions (50 F and rising) are critical and no moisture can be present. Roller speed is important to avoid pickup (less than 5 MPH) With proper pavement conditions an 8 to 10-year life extension is possible. Mass DOT uses primarily as an (SAMI) interlayer prior to placing a thin overlay.
Generally placed on higher volume roads. Depending on weather conditions the chip seal needs to cure from 2 -14 days prior to application of micro surface. Cape seals are selected mainly for visual and political reasons, although they perform better than chip seals and thin overlays in most locations. Kentucky TC found cape seal performance is better than standard 1 mill & fill.
Most states use polymer emulsion and many fog seal afterwards. Many states place on roads over 10,000 ADT. Most DOTs sweep the chip seal as soon as possible after construction. Agencies are interested in fractionated RAP in chip seals. New Mexico is using 100% RAP in some districts. Some states are using lightweight aggregate. West Virginia DOT requires an equipment calibration on every project. Snowplow damage is a factor when drivers are not trained. Louisiana DOTD requires a pavement moisture check prior to placement. Minnesota DOT incentive/penalty on aggregate passing the No. 200 sieve. Incentive for every 0.1% cleaner and penalty for every 0.1% dustier. Montana DT chip seals shortly after the completion of all new HMA construction.
Recycling the upper 3 to 4 inches of asphalt pavement requires at least another 3- inches of asphalt below to support the recycling train. Good specifications and mix designs are critical for success. The process is dependent on weather and needs dry conditions. If recycling to a 4 depth, two lifts are needed for best compaction. A recycled pavement is allowed to dry from 3 to 14 days with moisture testing following to ensure it is sufficiently dry before a new surface is placed on top. Most states cover CIR projects with 2 HMA overlay.
After initial construction joint sealing, few DOTs reseal the joints.
Most states only blow out the cracks and apply the sealant. Except in a few states routing is seldom done. Crack width beyond inch to 1-inch routing and sealing is no longer considered. Most pavement management systems do not recognize or give life extending benefits for crack sealing. Crack sealing is not done on pavements having issues with asphalt stripping. It s best to schedule crack sealing at least six months prior to paving. Some DOTs use mastics to fill open longitudinal joints. Mastics are becoming popular with DOTs because of good performance. It doesn t cause problems during HMA overlay construction and works on concrete spalls.
Some DOTs use diamond grinding to correct friction issues. Some DOTs use diamond grinding to remove studded tire and chain wear damage. Minnesota DOT has two smoothness specs. For urban areas, the IRI is below 90 inches/mile and other locations the IRI is below 60 inches/mile. Texas I-10 in Houston (270,000 ADT) is seeing good skid numbers, ride numbers, and reduced noise with the Next Generation Concrete Surface (NGCS). Sometimes there is an issue with slurry disposal from diamond grinding.
Some DOTs have established a minimum slab thickness requirement of 8 inches. Some DOTs skip DBR repairs when longitudinal cracking is present. Most DOTs use three 1 -inch diameter dowel bars in each outside lane wheel path. Inspection is necessary to check the alignment of slots and dowel bars.
Most agencies require the manufacturer to dilute the asphalt emulsion. Many DOTs require fog sealing rumble strips after construction. Fog sealing after chip sealing promotes a positive public perception. A few days after the chip seal is constructed it s fog sealed at 0.08 to 0.1 gal/yd2. Fog seals are always overlapped at the centerline and shoulder joints.
Most states combine full depth and partial depth repairs in the same project. Inspection is an issue for many DOTs. Better guidance is needed for the selection of dowel bars (stainless, zinc clad, fiber, O-dowels) and coatings. Several states are using pre-cast panels. Super slab system is gaining popularity.
Use only companies with well maintained equipment and experienced operators. Finding good candidate projects is challenging. Crack sealants can cause smoke. A better acceptance procedure is needed for the process. DOT personnel are very favorable about the ARRA training and field trips. Many local agencies are using HIR followed by a surface treatment.
Workmanship and variability between contractors is an issue in many DOTs. Some states need more contractors to increase competition. Some states are seeing delamination issues with micro surfacing. Iowa DOT specifies 6-12% residual asphalt by dry weight of aggregate. Minnesota DOT increased emulsion application range to 13-16% for better performance. Minnesota DOT required micro surfacing test section placed at night- at least 1 hour after sunset and at least 1 hour before sunrise. One lane @ 1000 ft. Montana DT implemented an incentive and disincentive for ride quality. DOT personnel are very favorable about the ISSA Slurry Systems Workshop.
Repairs should go to a depth of T/3 ( slab thickness). Defective concrete is removed either by jack hammer or milling. Milled areas are required to create a 30 to 60-degree slope for better bonding of repair material. Most DOTs are using either TechCrete, Fibercrete, or Aquafin Pavemend to make partial depth repairs. Some repair products can gum up diamond grinding blades.
Need guidance developed to properly evaluate rejuvenators. Pavement surface on high speed routes must be re-texturized before application. Tennessee DOT uses a polymerized rejuvenator over new HMA longitudinal joints.
States advise developing criterion for scrub seal pavement selection and avoid pavements with fatigue cracking and roads with steep grades. Some DOTs are reviewing pavement preparation to determine whether blowing the cracks clean will add to the treatment performance. Tennessee DOT always removes thermoplastic markings before scrub seal. Wait 30-days after completion before covering with surface treatment. Advise developing criterion for scrub seal pavement selection and avoid pavements with fatigue cracking and roads with steep grades. Scrub seals are sometimes used on severely cracked pavements as a stress absorbing membrane interlayer (SAMI) prior to micro surfacing.
Many contractors entering the market without good experience. Best performance when PCI is 80 or better. Latex modified emulsions used on higher volume roads and streets. More slurry seals are being placed to avoid ADA requirements. Used predominately by cities and counties. Some local agencies experience problems with forged slurry seal mix designs.
Most DOTs limit pavement preservation thickness to 1 inch or less. Thin 4.75 mm Superpave mixes placed at 90 lbs/yd2(7/8 ) are gaining popularity. Alabama DOT uses open-graded friction course (OGFC) placed from 90 135 lbs/yd2. Over rolling by the contractor can reduce the OGFC ability to drain.
Rumble strips should be removed prior to UTBWC placement. Many agencies require the use of a material transfer vehicle (MTV). DOTs prefer the spray pavers with larger emulsion tanks to reduce stopping for refilling. A separate pay item for asphalt emulsion is recommended. The spray paver benefits include a stronger bond to the underlying pavement, a barrier against moisture intrusion, and elimination of getting tack on vehicles. Many agencies want spray pavers to be the workhorse of the future. The quality of construction is generally improved but few spray pavers are available. Winter maintenance can be a problem if crews are not aware of how to treat them with deicing chemicals.
The DOTs have lost staff with experience and training is needed. Few agencies have any training in pavement preservation. Training is often attended by managers and not by the project field staff (inspectors). Many state personnel want hands-on training with equipment More work is going to consultants and DOTs struggle to keep them trained. Kentucky TC hired dedicated personnel to go around the districts and train chip seal inspectors on the job. Minnesota DOT uses Knowledge Book an interactive document in PowerPoint format to capture knowledge from retiring DOT experts.
Some states do not require a QC plan from pavement preservation contractors. Certification is required for lab and material sampling personnel. Many states have had bad experiences with warranties. Need a method to sample micro surfacing during placement. Kentucky TC formed internal agency group named the preventive maintenance alliance that meets twice a year and intends to improve treatment quality.
Some states designate 25 - 30% of total budget to pavement preservation. Many states don t track PE or CE costs on pavement preservation projects. States only consider using LCCA for new construction and not for preservation. Washington State DOT is converting 3,000 miles of HMA roadway to chip seals and achieved $120M is savings since 2009.
