Pavement Materials, Design & Performance Overview

Transcription

1 A U.S. Department of Transportation University Transportation Center Pavement Materials, Design & Performance Overview Pavement Resource Program (PRP)

2 The Pavement System >>

3 The Pavement System >> Comprised of asphalt binder, stone, and sand Must provide a smooth and safe riding surface that is durable and strong Asphalt performance highly dependent on both traffic speed (loading) and asphalt temperature at the time of loading

4 The Pavement System >> Foundation for the surface layer that must support and distribute the load from traffic Should maintain dry pavement and limit frost penetration damage to soil below (subgrade layer)

5 The Pavement System >> Natural soil under the pavement Performance is more susceptible to seasonal variations (i.e., freeze/thaw) and natural variations

6 Pavement Structure in New Jersey >> New Jersey focuses on using asphalt as a surface layer Rehabilitation is less expensive Faster construction/road opens sooner to traffic Quieter than concrete Allows for porous pavements that reduce splash and spray (i.e., better wet weather safety)

7 Pavement Materials, Design & Performance Overview Asphalt Mixture Design & Materials

8 4 Steps of Superpave Mix Design >> 1. Materials Selection 2. Design Aggregate Structure 3. Design Binder Content 4. Moisture Sensitivity

9 Performance Graded (PG) Asphalt Binders >> Construction Rutting Fatigue Cracking Low Temp Cracking Rotational Viscometer Dynamic Shear Rheometer (25mm) Dynamic Shear Rheometer (8mm) Bending Beam Rheometer and Direct Tension Various equipment/testing of binder properties

10 Structural vs. Functional Asphalt Material >> Structural Asphalt Materials/Overlays Increase strength of pavement system to limit/eliminate rutting and cracking Commonly used for most roadway applications Functional Asphalt Material/Overlays Used in specific locations to generally improve skid resistance, wet weather safety, and pavement related noise Common locations are on higher speed, non intersection type roads (i.e., highways, interstates) Common asphalt overlays include Open Graded Friction Course (OGFC), NovaChip, and Stone Matrix Asphalt (SMA)

11 OGFC Safety Benefits >> How OGFC reduces hydroplaning & wet weather accidents: New Generation Open Graded Mix: Greater than 18% Air Voids Air Voids Conventional Mix: Less than 7% Air Voids Rain falls onto paving surface and drains away through first layer Water stands on surface causing backspray; increases risk of hydroplaning

12 OGFC Reduces Splash & Spray >> Open Graded Friction Course (OGFC) Conventional Mix

13 Example: Wet Weather Crashes on I 95 >> Conventional Mix After OGFC Applied Year Change Total Number of Crashes % Dry Weather Crashes % Wet Weather Crashes % Fatalities % Total Injuries % Annual Rainfall (in inches) % Total Rain Days %

14 Pavement Materials, Design & Performance Overview Pavement Design & Analysis

15 Mechanistic Empirical Pavement Design (MEPDG) >> MEPDG developed during six year, multi million dollar national research project New methodology that uses measured material properties instead of outdated statistical relationships More realistic design/analysis using MEPDG results in more cost effective roads CAIT is providing training and workshops on using MEPDG to NJDOT and their consultants AASHTO Road Test 1950s

16 MEPDG Design Model >> Climate considerations Load considerations Materials selection Data and testing informs future designs Calculations/Data Pavement response Damage accumulation Distress

17 Pavement Materials, Design & Performance Overview Pavement Noise Evaluation

18 Tire Related Noise: Main Causes >> Driving Direction (1) Tread Impact (2) Air Pumping Resonance (3) Tread Snap out

19 CAIT Pavement Noise Testing >> Tire/pavement noise depends on: Pavement surface texture Pavement material (asphalt or concrete) Tire tread configuration Vehicle speed Tire/pavement noise measurements On board sound intensity (OBSI) Noise levels at pavement surface CAIT conducting ongoing noise research with NJDOT

20 Pavement Noise: Asphalt vs. Concrete Actual noise testing conducted by CAIT Pavement Resource Program

21 NJDOT Quiet Pavement Pilot Program (QPPP) >> FHWA s Quiet Pavement Stance FHWA does not allow federal funds to be spent on using pavement surface to mitigate pavement noise Must demonstrate to FHWA reduced noise levels and noise reduction is sustainable CAIT is working with NJDOT on QPPP materials and long term evaluation Quiet Pavement Benefits Noise walls cost = $3 million per lane mile OGFC cost = $200,000 per lane mile Even after expense, noise walls do nothing to address aging/deteriorating pavement OGFC application would reduce noise, improve pavement condition, and address the noise at the source

22 Pavement Materials, Design & Performance Overview Sustainability in Transportation Infrastructure

23 Sustainability in Transportation Infrastructure >> Areas of Environmental Stewardship Noise reduction Recycled materials Warm mix asphalt (WMA)

24 Benefits of Using Recycled Materials >> Environmental and economic benefits to using recycled materials: Saves raw resources (i.e., aggregate, asphalt liquid) Mitigates disposal costs and reduces load in landfills Potential to recoup costs through LEED credits Holds potential for jobs creation (e.g., Lakewood tire recycling plant) Common recycled materials used in pavement are: Recycled tires turned into crumb Recycled asphalt pavement; a byproduct of milling up old pavement Recycled concrete aggregate; rubblized from old roads and reused as a base course (common in areas without ready access to quarries)

25 Recycled Tire Rubber (Crumb) >> Used tires are shredded down to crumb sized particles and mixed with asphalt Crumb is added to asphalt to modify properties NJDOT uses crumb in OGFC mixes, also known as quiet pavements Approximately 1,000 recycled tires used for every one lane mile paved NJDOT has used more than 300,000 recycled tires in last 3 years

26 Recycled Asphalt Pavement (RAP) >> Most recycled product in world (by weight); byproduct of milling old pavement RAP mixed with new asphalt (saves on new aggregate and binder) But old binder in RAP limits the amount that can be effectively used in mix CAIT helping NJDOT research new methods/technologies so higher percentage of RAP can be used without sacrificing pavement performance

27 Field Issues with Rap: NJ I 195 >> LTPP SPS 5 Sections: 2 Inch Overlay after Milling LTPP SPS 5 Sections: 2 Inch Overlay with No Milling

28 Warm Mix Asphalt (WMA) >> Asphalt material produced at lower temps Conventional hot mix produced at more than 325 F WMA produced at less than 265 F Reduces energy consumption Reduces emissions Less impact on air quality Worker safety and health risks reduced CAIT and NJDOT researching new WMA methods and technologies Conventional Mix 311 F WMA 230 F

29 Questions? cait.rutgers.edu/prp