1. CIVIL ENGINEERING APPLICATIONS OF TIRE DERIVED AGGREGATE
Dana N. Humphrey, Ph.D., P.E. Professor of Civil Engineering University of Maine
Presented to:
CIWMB Waste Tire Forum March 9, 2006

2. Tire Derived Aggregate – TDA

3. Why use TDA? TDA has properties that civil engineers need
Lightweight (1/3 soil)
Low earth pressure (1/2 soil)
Good thermal insulation (8 times better)
Good drainage (10 time better)
Compressible
Vibration damping

4. Why use TDA?
TDA is often cheapest alternative if you need their unique properties

5. Why use TDA? Can use lots of tires!!! 75 tires per C.YD. of TDA fill
600,000 tires for Dixon Landing Interchange, Milpitas, CA
75,000 for vibration damping layer in San Jose, CA
75,000 for retaining wall backfill in Riverside, CA
2 million for highway embankment in Sabatus, Maine

6. Civil Engineering Applications - United States vs. California -
Uses 21% of tires in U.S.
Uses 5% of tires in California

7. Range of civil engineering applications
Lightweight fill for highway embankments
Retaining wall backfill
Vibration damping layers for rail lines
Insulation to limit frost penetration
Drainage layers for landfills
Drainage layers for on-site wastewater treatment systems (A.K.A. septic tanks)

8. Specifications Type A – drainage, insulation & vibration damping
100% passing 4-in. sieve
Minimum of 90% passing 3-in. sieve
Maximum of 5% passing 4.75-mm (no. 4) sieve
Type B – lightweight fill
100% smaller than 18-in. max. dimension
90% smaller than 12-in. max. dimension
Maximum of 50% passing 3-in. sieve
Maximum of 25% passing 1.5-in. sieve
Maximum of 1% passing 4.75-mm (no. 4) sieve

9. Dixon Landing Interchange
PROBLEM: Embankment Constructed on Bay Mud
SOLUTION: Use TDA for the core of the embankment
CHEAPEST SOLUTION: Caltrans saved $470,000

10. Typical Cross Section

11. Unloading TDA

12. Spread with bulldozer

13. Compact with 10-ton roller

14. Conventional Lightweight Fill

15. Unit Costs Cost for common borrow = $7.48/yd3
Placement costs of TDA (including geotextile) = $3.74/yd3
Purchase & delivery costs of TDA (paid by CIWMB) = $23.66/yd3
In-place cost for TDA = $27/yd3
In-place cost for lightweight aggregate = $50/yd3

16. Cost Savings
Cost savings to CALTRANS with TDA provided at no cost by CIWMB = $477,000
Cost savings to state less purchase price of TDA = $230,000

17. Why use TDA for retaining wall backfill?
Low unit weight (50 pcf)
Free draining (k > 1 cm/s)
Good thermal insulation (8 x better than soil)
75 tires per YD3!

18. Rt. 91 Wall in Riverside, CA Freeway widening
Objective: show that reduced earth pressures can reduce overall wall construction costs
Length: 260 ft
Tires used: 75,000 PTE

19. Rt. 91 wall cross section

20. Compacting TDA

21. Potential Future Savings for Walls
Lower pressure on wall  less rebar
Potential reduction = 28 tons/100 ft
Potential cost savings = $13,000/100 ft

22. Vasona Light Rail Project

23. Vasona Light Rail Project

24. Vasona Light Rail Project Design
12-in. ballast stone
12-in. subballast gravel
12-in. of TDA wrapped in geotextile

25. Vasona Light Rail Project Monitoring

26. Vasona Light Rail Project Cost Savings
Cost of conventional track = $100 per track-ft
Cost of track with TDA vibration mitigation = $121 per track-ft
Cost of floating slab vibration mitigation = $ per track-ft
Cost savings = $479-$879 per track-ft
Total savings = $1 to $2-million

27. Future of TDA in California
Two wall projects Spring/Summer, 2006
Caltrans HQ requires TDA as first choice for lightweight fill
Need to develop more projects at municipal/county level
Need more processors that can efficiently make Type B TDA
Significant potential for growth

28. QUESTIONS?