TIRE DERIVED AGGREGATE - A New Road Building Material - BARRIERS AND OPPORTUNITIES

Transcription

1 TIRE DERIVED AGGREGATE - A New Road Building Material - BARRIERS AND OPPORTUNITIES Dana N. Humphrey, Ph.D., P.E. Professor of Civil Engineering University of Maine Presented at: Recycled Materials in Road and Airfield Pavement June 25, 2005

2 Barriers to Recycled Materials Engineering Engineering properties unknown Long term performance unknown No real engineering benefit Lack of design standards Highway engineers are risk adverse

3 Barriers to Recycled Materials Environmental Chemical composition unknown Long term environmental effects unknown Public perception it is a waste, so it must be bad! Convoluted regulatory approval process Environmental regulators are risk adverse

4 Barriers to Recycled Materials Construction New procedures and equipment required Difficult to estimate in-place cost Supply is uncertain both quantity & quality More expensive that conventional construction Contractors are risk adverse

5 Overcoming the barriers Lab studies to determine engineering properties Lab studies to determine environmental properties Pilot construction projects (full or near-full scale) Full scale construction projects monitor engineering and environmental performance Modify specification, etc. as needed National standards Education, education, education address concerns head on and focus on the benefits

6 Tire Derived Aggregate TDA

7 Benefits of 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

8 Benefits of TDA TDA is often cheapest alternative if you need their unique properties

9 Benefits of TDA Can use lots of tires!!! 100 tires per C.M. of TDA fill 400,000 tires for landslide stabilization, Topsham, Maine 1.2 million tires for highway embankment, Portland, Maine

10 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

11 Civil Engineering Applications in United States The fastest growing use for scrap tires Approximately 60 million tires per year are used in these applications

12 Specifications Type A drainage, insulation, vibration damping 100% passing 100-mm sieve Minimum of 90% passing 75-mm sieve Maximum of 5% passing 4.75-mm (no. 4) sieve Type B lightweight fill 100% smaller than 450-mm max. dimension 90% smaller than 300-mm max. dimension Maximum of 50% passing 75-mm sieve Maximum of 25% passing 38-mm sieve Maximum of 1% passing 4.75-mm (no. 4) sieve

13 Guidelines ASTM D6270 Civil Engineering Applications of Scrap Tires Guidelines to limit heating Water quality

14 Guidelines to limit embankment heating No TDA contaminated with gasoline, oil, grease, etc. Maximum of 50% passing 75 mm sieve Maximum of 25% passing 38 mm sieve Max. of 1% passing No. 4 (4.74 mm) sieve 3-m max. TDA layer thickness Minimize access of fill to water & air

15 Dixon Landing Interchange PROBLEM: Embankment Constructed on Bay Mud SOLUTION: Use TDA for the core of the embankment CHEAPEST SOLUTION: saved $230,000

16 Typical Cross Section LOW PERMEABILITY SOIL COVER TWO TIRE SHRED LAYERS EACH LAYER UP TO 10 FT THICK COMPRESSIBLE BAY MUD

17 Unloading TDA

18 Spread with bulldozer

19 Compact with 10-ton roller

20 Conventional Lightweight Fill

21 Unit Costs Cost for common borrow = $7.48/yd 3 Placement costs of TDA (including geotextile) = $3.74/yd 3 Purchase & delivery costs of TDA = $23.66/yd 3 In-place cost for TDA = $27/yd 3 In-place cost for lightweight aggregate = $50/yd 3

22 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

23 TDA temperature Sensor Station Temperature in (deg. C) /8/01 7/28/01 9/16/01 11/5/01 12/25/01 2/13/02 4/4/02 Date # 1 # 3 # 7 # 8 # 14 # 15 # 27

24 Conclusions Barriers to using recycled materials can be overcome TDA has properties that engineers need Civil engineering applications is fastest growing use for scrap tires in U.S. Specifications and guidelines available Negligible environmental effects

25 QUESTIONS?