Mechanical Properties of Recycled Asphalt Shingles at Constant and Elevated Temperatures

1. Department of Civil and Environmental Engineering Recycled Material Resource Center (RMRC) Mechanical Properties of Recycled Asphalt Shingles at Constant and Elevated Temperatures Ali Soleimanbeigi, PE PhD student, University of Wisconsin-Madison

2. Recycled Asphalt Shingles (RAS) • 80 % of homes are roofed by asphalt shingles • 12 million tons asphalt shingle waste per year in US • 400,000 tons in Wisconsin • Current applications reuses 10-20 % of asphalt shingle waste • RAS is a top priory for reuse (EPA, FHWA) Embankment fill Reuse application with large volume Retaining wall backfill

3. Shape and component of RAS • Angular • Rough surface texture • Porous • Plate like particles • Highly angular • Rough surface texture RAS Bottom Ash (BA)

4. Mechanical Properties for Structural Fill • Shear Strength: stability • RAS:BA mixture or stabilized RAS has sufficient shear strength as structural fill (f> 32o) • Compressibility:settlement • Compressibility is limited by adding granular material like BA or by stabilization • Hydraulic Conductivity: drainagecapacity • RAS:BA mixture or stabilized RAS has sufficient drainage capacity as structural fill, K > 10-4 cm/s RAS contains asphalt cement, therefore: Effect of seasonal temperature change on mechanical properties of compacted RAS:BA mixture

5. Thermo-mechanical system: Triaxial Cell

6. Thermo-mechanical system: Consolidometer

7. Thermo-mechanical system: Permeameter Thermocouples Copper tubing Heating bath

8. Effect of temperature change on shear strength of RAS:BA mix and stabilized RAS

9. Effect of Temperature Change on Shear Strength and Volume Change RAS Soil

10. Shear Strength of RAS:BA mixture at Different Temperatures Shear strength Friction T=5oC 10 15 20 25 30 T=35oC Cohesion c≈0 kPa at different T • Compacted RAS:BA mixtures have sufficient shear strength for typical highway embankment fills

11. Shear Strength of Stabilized RAS at Different Temperatures f Stabilized RAS c Outwash Sand • Sufficient shear strength at elevated temperatures for structural fill

12. Effect of temperature change on compressibility of RAS:BA mix or stabilized RAS

13. Long Term Compressibility Variation of strain over time under constant load sv Time, t (log scale) tp ev 1 h Soil Cae ev tp: End of primary consolidation time Cae: Secondary compression ratio

14. Compressibility at Elevated Temperatures 24 h Increase of temperature increases the vertical strain and vertical strain rate

15. Model Verification

16. Variation of caewith RAS Content and Temperature

17. Effect of Thermal Preconsolidation-RAS:BA (25%:75%) s’v=25 kPa 50 kPa 25 kPa 100 kPa 50 kPa 100 kPa 200 kPa Cae= 0.0080 200 kPa Cae= 0.0004 T=35 oC T=22 oC • Construction at warm seasons greatly reduces the long term compressibility of RAS:BA mixture

18. Effect of Thermal Preconsolidation-Stabilized RAS T=22oC cae=0.0016 T=22oC T=35oC cae=0.0002 T=22oC • Construction at warm seasons greatly reduces the long term compressibility of stabilized RAS

19. Effect of Temperature on Hydraulic Conductivity • Hydraulic conductivity of RAS:BA mixture increases with increase in temperature Hydraulic conductivity increases with temperature

20. Conclusions • Sufficient shear strength of RAS:BA mix or stabilized RAS is maintained due to seasonal temperature change • Thermal cycle increases shear strength and stiffness of RAS:BA mix • Secondary compression ratio is an exponential function of temperature • Construction of embankment fills using RAS:BA mix or stabilized RAS is recommended during warm seasons • Use of RAS will contribute to more sustainable roadway construction

21. QUESTIONS?

22. Effect of Thermal Cycle 9% reduction of ea T=35oC 22oC 22oC • Thermal cycle increases the shear strength and stiffness of the compacted RAS:BA mixture