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

Tire Derived Aggregate – TDA

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

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

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

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

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)

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

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

Typical Cross Section

Unloading TDA

Spread with bulldozer

Compact with 10-ton roller

Conventional Lightweight Fill

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

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

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!

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

Rt. 91 wall cross section

Compacting TDA

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

Vasona Light Rail Project

Vasona Light Rail Project

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

Vasona Light Rail Project Monitoring

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 = $600-1000 per track-ft Cost savings = $479-$879 per track-ft Total savings = $1 to $2-million

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

QUESTIONS?