California Asphalt Rubber Case Studies

1

• California Asphalt Rubber Case Studies Reduced
  Thickness

Jack Van Kirk Basic Resources
2
Presentation Outline

• What is Asphalt Rubber
• Where has it been used successfully
• Caltrans reduced thickness design guidelines and
  supporting research
• Cost-effective strategies
• Advantages of asphalt rubber

3
Definition of Asphalt Rubber

• Uses a minimum of 20 /- 2 crumb rubber
• Uses 2mm size crumb rubber
• Reacts/interacts crumb rubber for a minimum of 45
  min. at elevated temperatures
• Modifies original properties of asphalt cement

4
Crumb Rubber Modifier
5
Ground tire rubber is received in 2,000 pound
Supersacks.
6
Current Use Asphalt Rubber Strategies

• Asphalt Rubber Hot Mix (ARHM)
• Asphalt Rubber Chip Seal
• Asphalt Rubber Cape Seal
• Multi-Layer Systems

7
Where have Asphalt Rubber strategies been used
successfully?
8
Caltrans Reduced Thickness Design Guideline

• Caltrans developed the guidelines
• in 1992
• Based on laboratory and long-term field data (two
  decades)
• Supported by research efforts

9
Design of Asphalt Rubber Pavements

• Uses a deflection based design method
• Up to 50 reduction in thickness compared to
  conventional AC design thickness
• Over 1000 reduced thickness projects

10
(No Transcript)
11
Ravendale Project

• First project to use reduced thickness Asphalt
  Rubber pavements when compared to the
  conventional AC design thickness
• Different thickness test sections of Asphalt
  Rubber and conventional AC mixes were placed for
  comparison

12
75mm 45mm 45mm 45mm
75mm 45,60,75,150mm
13
(No Transcript)
14
(No Transcript)
15
45mm AR over SAMI 16 yrs old
16
45mm AR over SAMI 16 yrs old
17
75mm AR over SAMI 16 yrs old
18
75mm AR over SAMI 16 yrs old
19
Council On Scientific and Industrial Research
(CSIR)

• Caltrans conducted a research project with CSIR,
  UCB, and Dynatest Consulting to verify the
  reduced thickness theory for Asphalt Rubber
  pavements
• The research used accelerated pavement testing
  (APT) using the heavy vehicle simulator (HVS)
• The research included laboratory testing to
  support the field testing

20
(No Transcript)
21
(No Transcript)
22
Original condition of pavement in South Africa
23
75 mm Conv. AC
25 mm ARHM
38 mm ARHM
24
Performance
 
25
Supporting Research

• UAF (Raad) - Conducted laboratory beam fatigue
  testing of ARHM-GG and conventional DGAC and
  concluded that ARHM-GG had significant
  improvement in fatigue properties
• OSU (Hicks) and UNR (Epps) - Conducted life cycle
  cost analysis and concluded that Asphalt Rubber
  was more cost-effective when compared to
  conventional AC pavement maintenance and
  rehabilitation strategies

26
Asphalt Rubber 3-Layer Systems

• Asphalt Rubber binder used in hot mix and chip
  seals can be used in different thin layer
  systems
• These systems can save hundreds of thousands of
  dollars when compared to full reconstruction
  using conventional strategies

27
Asphalt Rubber SAMI

• Caltrans conducted field trials using Asphalt
  Rubber stress absorbing membrane interlayers
  (SAMI)
• In 1991 Caltrans concluded that SAMIs in AC
  overlays of AC pavements with aggregate base are
  equivalent to approximately 52mm of AC in
  retarding initial cracking

28
(No Transcript)
29
Randolph AvenueCosta Mesa, CA
30
10 years old
37mm ARHM-GG ARCS 25mm AC
31
Philadelphia StreetWhittier, CA
32
10 years old
37mm ARHM-GG ARCS 25mm AC
33
Thin Asphalt Rubber Overlays
Los Angeles, CA
34
25mm ARHM-GG 1 year old
35
5 years old
36
10 years old
37
Advantages of Asphalt Rubber Binder

• Significantly higher binder contents
• - 20 higher in dense graded mixes
• - 40 - 50 higher in gap graded mixes
• - 50 - 60 higher in open graded mixes
• Thicker film thickness
• Reduced oxidation
• Increased durability
• Increased resistance to reflective cracking

38
Advantages of Asphalt Rubber Pavement Strategies

• More abrasion resistant
• Reduced oxidation
• Increased fatigue resistance
• Can reduce thickness
• Reduced construction time/Increased safety
• Savings in energy and natural resources
• Lower maintenance cost

39
Why choose Asphalt Rubber strategies?

• Has a long term performance history (over 30
  years)
• Over 1000 successful reduced thickness projects
• Proven alternative to costly reconstruction
• Established life cycle cost-effectiveness

40
Asphalt Rubber Performance
Thank you!