DESIGN & CONSTRUCTION TECHNIQUES FOR LONGER LASTING ASPHALT PAVED ROADS

Transcription

1 DESIGN & CONSTRUCTION TECHNIQUES FOR LONGER LASTING ASPHALT PAVED ROADS Doug Buth Area Manager, Payne & Dolan, Inc. Kenneth R. Ward, P.E. Vice President, Ruekert & Mielke, Inc. Steve Pease Construction Review Technician, Ruekert & Mielke, Inc. Kenneth R. Ward, P.E. Vice President, Ruekert & Mielke, Inc. Doug Buth Area Manager, Payne & Dolan, Inc. Steve Pease Construction Review Technician, Ruekert & Mielke, Inc.

2 Agenda Introductions & Welcome 10:00-10:10 Presentation 10:10-11:40 Complimentary Lunch & Networking 11:40-12:00 Payne & Dolan Plant Tour 12:15-12:45

3 Program Overview Road Design Soils Base Drainage Pavement Road Construction Base Pavement

4 Road Design New road or full reconstruction. Road maintenance overlays and repairs. Use the same base methods to determine your needs. Soils Drainage

5 Road Design Soils Know soil types Take soil borings Know how to interpret the soil boring logs CBR (California Bearing Ratio) WAPA information

6 Soil Borings A low-cost investment to determine long-term needs. Ten 10-foot deep borings cost about $3,500. One mile of 2 overlay costs about $345,000. One mile of full reconstruction costs about $1,800,000.

7 Soil Borings Where should they be taken? How many?

8 Soil Borings

9 Soil Borings

10 Soil Borings Failure to follow the information from the borings.

11 Road Design Undercutting Soils How deep? Geotextile Reinforcement Geogrid Reinforcement Separation Layers Reinforcement Layers

12 Road Design

13 Road Design Drainage Keep drainage below the base. Rural Considerations Urban Considerations

14 Road Design Rural Considerations Keep ditch grades at 1% when feasible. Keep the bottom of the ditch 6 inches below the subgrade.

15 Road Design Urban Sections Curb and Gutter Storm Sewer Double inlets at low points. Edge Drains/Drain Tiles

16 Road Design Avoid vertical curves at grade breaks less than 2%. Consider increasing cross slope to 3%.

17 Road Design Road Base Design Base Types Depth Thickness Open Graded vs Non-Open Graded Frost Layers Type Depth

18 Road Design Other Considerations Clear Zone Multi-Use Paths

19 Road Design Pavement Design Material Specification Thickness/Loadings

20 HOT MIX ASPHALT DESIGN, PRODUCTION & CONSTRUCTION

21 Who s the Walbec Group?

22 Balance = Success

23 What is HMA made of? Aggregates (93-96% by weight) Load bearing components of the mix Skid resistance, stability, workability PG binder (4-7% by weight)- a.k.a. Asphalt Cement Glue or muscle that holds everything together Flexibility, durability Air Allows proper compaction for the pavement to remain flexible

24 Primary Aggregate Sources Sand and Gravel All the Ingredients In One Deposit More Difficult to Balance Inventory Different Compositions of Deposits Limestone Drilling and Blasting Absorption Specific Gravity Granite Drilling and Blasting Crushing Antistrip

25 Typical HMA Mix Ingredients 7/8 X 5/8 Chip 5/8 X 1/2 Chip 1/2 X 1/4 Chip Manufactured Sand Natural Sand R.A.M. Asphalt Cement

26 Aggregate Properties Aggregates have several physical properties that are of importance to the asphalt pavement designer: Gradation & Size Particle Shape/Angularity Toughness/Durability Soundness/Wear Freeze Thaw Cleanliness (deleterious materials) Absorption Specific Gravity Adhesion Surface Texture

27 Recycled Materials RAM (Recycled Asphaltic Materials) RAP-Reclaimed Asphaltic Pavements FRAP RAP fractionated into Different Sizes RAS-Recycled Asphalt Shingles Stockpile sampling/testing same as any other aggregate source. Extractions required to adjust asphalt contents. Controlled by binder replacement percentage and not by weight.

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30 WisDOT Standard Specification 460

31 PG Binder (a.k.a. -Asphalt Cement) Asphalt cement is a viscoelastic material (viscous properties at high temperatures and elastic properties at low temperatures). Asphalt is a thermoplastic material that softens as it is heated and hardens when cooled.

32 PG Binder Grading PG P PG+ Designation *If sum of 2 numbers is greater than 92 modification is required Performance Grade Average 7-day max pavement design temp ( 58 o C / 136 o F ) To Resist Rutting Min pavement design temp ( - 28 o C / - 18 o F ) To Resist Cracking

33 PG Binder Modification Styrene Butadiene Styrene (SBS) Polyphosphoric Acid (PPA)

34 New Binder Grading Protocols Old E-mix Grade New T-mix Grade S 64-28P H 70-28P V S 64-34P H V

35 Superpave Mix Design Superpave Design Looks at Pavement Performance: Asphalt Binder Grades related to regional temperature. Aggregates properties are specified and quantified. Mix Design testing better simulates field conditions. All aspects are based on traffic loading (ESALs). Equivalent Single Axle Loads Based Off of 20 years

36 Mix Design Process 4 STEPS OF A SUPERPAVE MIX DESIGN

37 HMA Mix Design The amount of air voids measured in the HMA mixture is the most important factor in predicting HMA pavement performance. 3-5% air voids has historically proven to provide the best pavement performance. Compaction specifications require ~10% air voids (or min. 89.5% density). After 3 years of traffic loading, the pavement air voids reduce to ~4%.

38 Air Voids Relationships Durability low high Stability 4% Air Voids (V a ) (For a given aggregate structure)

39 Air Void Regression Current WDOT spec. requires that all mixes are regressed from 4% to 3% air voids utilizing liquid Asphalt Cement (AC). Mixes will contain more liquid AC. Less cracking. More density in Longitudinal Joints. Longer pavement life.

40 WDOT Bid Item Coding (a.k.a. T-mixes) 4 LT S Gradation Traffic Level Binder Grade Binder Traffic Designation

41 Step 1: Gradation (Nmas) E-Mixes Lower Layer Options 25.0 mm 19.0 mm 12.5 mm Upper Layer Options 12.5 mm 9.5 mm 4.75 mm T-Mixes mm mm mm mm mm mm

42 Step 2: Traffic Level E-Mixes T-mixes Load Category E0.3 <300,000 E1 E3 E10 E30 E30X ESALs 300,000 to < 1 million 1 million to <3 million 3 million to <10 million 10 million to <30 million >30 million Category LT MT HT ESALs < 2 million 2 million to <8 million >8 million SMA Not Rated SMA consider for >5 million Don t increase your traffic category to create a factor of safety.

43 Step 3: Binder Grade Southern Asphalt Zone All layers, all types of construction (replacement, overlays, reconstructs, etc ) PG 58-28

44 Step 4: Binder Traffic Designation Binder grades to be based on expected traffic level: S Standard (Normal projects) H Heavy (Higher truck movements, roundabouts, turn lanes, etc ) V Very Heavy (Extreme traffic, stopping & starting) E Extremely Heavy (Toll Booths, Port Facilities-not part of the WI matrix) Example (old to new): PG 64-28P PG H H & V replace the P Grades If you re looking to create a factor of safety increase your binder traffic designation

45 Let s put it all together! Step 1 Step 2 Step 3 Step 4 Gradations (Nmas) Traffic Level Asphalt Binder Designation Level mm LT Low Traffic Vol. (40 gyrations) S Standard mm MT Medium Traffic Vol. (75 gyrations) H Heavy mm HT High Traffic Vol. (100 gyrations) V Very Heavy mm E Extremely Heavy mm mm

46 Drum Mix Plant Fundamental Components Aggregate Cold Feed Bins Conveyor And Aggregate Weighting System Drum Mixer Dust Collection System Hot Mix Conveyor Asphalt Binder Storage HMA Storage Silos Control House

47 Balancing Production vs. Placement Production at the facility, delivery to the job site, laydown by the paver, and compaction by the rollers must all be in tune to produce the highest quality pavement. Understanding the variables that can affect each rate is the key to adjusting the others when changes happen.

48 HMA Mix Transport HMA is usually loaded into a truck at a fairly uniform temperature between 280 F to 310 F. Several measures that can be taken to minimize HMA cooling during transport are: Avoid Cold Weather Paving!! Minimize Haul Distance Minimize trucks stacked up on the job Insulate Truck Beds/Tarps

49 Placing Mixture Compaction rule: +/-3/8 per inch of material laid versus compacted thickness

50 Placing Mixture When should you fold the wings? To minimize segregation, fold the wings as seldom as possible. Just enough to keep the mix in the wings from getting so cool that it won t go through the paver. How often will depend on delivery rate, mix temperature, and the air temperature. Folding the wings should only be done while the hopper is fairly full.

51 Placing Mixture What do you do if the next truck is not ready? Do not slowly pull it forward and run the hopper empty. Wait with a full hopper. This keeps the mix and paver warm, and the screed charged with a full head of material. When the truck arrives, have the bed raised and ready to flood the hopper. Start the paver, getting it to paving speed as quickly as possible. When the truck is picked up by the paver, release the gate and flood the hopper. If the paver frequently waits, a paver speed adjustment may be necessary. A transfer machine proper utilized eliminates this concern.

52 Transverse Joints A transverse joint must be constructed across the pavement whenever paving is being suspended (for the day, at the end of the job). When ending paving (for the day or the job), run the paver in normal fashion right up to where the transverse joint is being constructed. Do not run the paver dry right at the joint. Keep a full head of material in front of the screed to the end.

53 Longitudinal Joints The key to good longitudinal joint construction is the proper overlap of mix between the new and old mat. The proper overlap provides just enough material on top of the joint to allow proper compaction without having extra mix, which would have to be removed by a later.

54 Compaction Reasons for Compaction: Bring mix to desired air void content. Provide shear strength or resistance to rutting. Ensure the mixture is water resistant.

55 Factors Affecting Compaction Environmental Factors Mix Property Factors Construction Factors Temperature Aggregate Rollers Ground temperature Air temperature Wind speed Solar flux Gradation Size Shape Fractured faces Volume Type Number Speed and timing Number of passes Lift thickness Asphalt Binder Chemical properties Physical properties Amount Other HMA production temperature Haul distance Haul time Foundation support

56 Compaction Temperature 320 F F F F (140 F General Rule of Thumb

57 Typical Compaction Train Screed Breakdown Roller- Vibratory Steel Wheel Intermediate Roller- Pneumatic Tire Roller or Vibratory Steel Wheel Finish Roller- Static Steel Wheel Rollers Traffic

58 Vibratory Roller Amplitude: the greatest movement in one direction (up or down) of a vibrating roller drum from a position of rest. Frequency: the number of vibrations (downward impacts) per minute. Impact Spacing should be between 12 and 14 impacts per foot.

59 Roller Patterns Uniform compaction depends upon getting the same number of roller passes over each area of the mat. This means that a pattern must be developed that covers the entire mat with an equal number of roller passes from each type of roller. Overlap at least 6 inches. Turn roller slightly to the side to reverse or stop. End passes at different points. Do not roll over the crown. The first roller pass should ~ ft. away from the joint. Compact joints with the roller operating parallel to the joint.

60 Reality Check By design HMA (hot mix asphalt) is a flexible pavement. The quality of HMA is a direct correlation of the strength and stability of the foundation that it is laid upon. The weather and environmental impacts of our climate is harsh on pavements. Unfortunately all pavements will eventual crack, fail, and need rehabilitation. Maintaining pavements is crucial to there longevity.

61 Take Aways Utilize WDOT specifications on your projects Amend to fit your specific project needs Realize that amendments may increase or reduce project cost Enroll the help of those around you Ruekert & Mielke WAPA/Industry Avoid Cold Weather HMA paving!!! Realize many options are not a cure, they re a Band-Aid Fabrics Mix fibers additives Joint adhesives Joint heaters Partial depth repairs Consider upgrading your PG binder grade Consider Perpetual HMA Pavement (a.k.a. full depth HMA) Designed for crack from the top down not the bottom up Shorter construction duration in comparison to PCC Superior IRI ride compared to PCC Easier to maintain in comparison to PCC Will out perform PCC life cycle costs 193:perpetual-pavement&catid=196&Itemid=326

62 Construction Review 1. Acts as a liaison between contractor and the owner. 2. CRT knows the job. 3. Be observant and identify any potential problems. 4. Communicate with project manager and job foreman daily. 5. Communicate with the owner and the residence involved with the project. 6. Complete daily reports.

63 Daily Report

64 QUESTIONS? Doug Buth Area Manager, Payne & Dolan, Inc. Kenneth R. Ward, P.E. Vice President, Ruekert & Mielke, Inc. Steve Pease Construction Review Technician, Ruekert & Mielke, Inc. Kenneth R. Ward, P.E. Vice President, Ruekert & Mielke, Inc. Doug Buth Area Manager, Payne & Dolan, Inc. Steve Pease Construction Review Technician, Ruekert & Mielke, Inc.

65 Save the Date April 18, 2018 What's New in Storm Water: Regulations, Concepts, & Technologies R/M Waukesha, Conference Center May 16, 2018 Development Review Best Practices & Overcoming Administrative Hurdles R/M Waukesha, Conference Center May 30, 2018 Development Review Best Practices & Overcoming Administrative Hurdles Fitchburg Public Library (Madison Area)

66 Thank You! We appreciate your feedback. Watch for the survey.