3501-20 - Introduction to Superpave Strategic Highway...

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1 Introduction to Superpave • Strategic Highway Research Program (SHRP) was established by U.S. Congress in 1987 to conduct a 5-year study to improve the performance of roads in the U.S. • Of the U.S.$150 million budget, $50 million was spent on asphalt research. • SUPERPAVE (SU perior PER forming Asphalt PAVE ments) is a product of the SHRP asphalt research. • SUPERPAVE consists of: (1) Asphalt Binder Specification. (2) Mixture Design and Analysis System. SUPERPAVE BINDER TESTS 1. Pressure Aging Vessel (PAV) • Simulates long term (3-5 years) aging of binders in service. • Binders are aged in the standard RTFOT first. • 50 g samples placed in pans and placed in the PAV. • Up to 10 pans can be placed in the PAV. • PAV temperatures: 90, 100 or 110 °C • PAV pressure: 2.1 MPa (300 psi) • PAV time duration: 20 hours Bottom of pressure aging vessel Rack of individual pans (50g of asphalt / pan) Pressure Aging Vessel Vessel Lid Components
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2 Pressure Aging Vessel Courtesy of FHWA Integrated Pressure Aging Vessel 2. Dynamic Shear Rheometer Test • Measures the viscoelastic properties of a binder by testing it in an oscillatory mode. • Sample size: (1) 25 mm in diameter & 1 mm thick for softer binder. (2) 8 mm in diameter & 2 mm thick for harder binder. • Test temperatures: High and intermediate pavement temperatures. • Measured properties: G* &
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3 Dynamic Shear Rheometer Test Shear Stress = 2 T / r 3 Shear Strain = r / h G* = ( max - min ) / ( max - min ) 1 cycle Time A A B C C A B Fixed Plate Oscillating Plate Test operates at 10 rad/sec or 1.59 Hz 360 o = 2 radians 1 rad = 57.3 o Schematics of Oscillating & Fixed Plate in the DSR
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3501-20 - Introduction to Superpave Strategic Highway...

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