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Asphalt The Bottom of the Barrel Sponsored by: Minnesota LTAP Center Presented by: Michael Marti, P.E. SRF Consulting Group, Inc. Dan Wegman, P.E. SemMaterials.

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Presentation on theme: "Asphalt The Bottom of the Barrel Sponsored by: Minnesota LTAP Center Presented by: Michael Marti, P.E. SRF Consulting Group, Inc. Dan Wegman, P.E. SemMaterials."— Presentation transcript:

1 Asphalt The Bottom of the Barrel Sponsored by: Minnesota LTAP Center Presented by: Michael Marti, P.E. SRF Consulting Group, Inc. Dan Wegman, P.E. SemMaterials

2 Crude Oil Distillation % Volume Boiled Off Butanes & Lighter Gasoline Naphtha Kerosene/Jet Fuel/Diesel Gas Oils Atmospheric Light Vacuum Heavy Vacuum Resid

3 Asphalt Cement (AC) End product - crude oil distillation Chemistry –crude source –refining method Chemistry Physical Properties Performance

4 Primary use of AC Hot Mix Asphalt (HMA) Aggregate AC Mix Plant Paving

5 AC Quality Three major failure modes: –Rutting (AC too soft at high temperatures; aggregate structure not strong enough) –Thermal cracking (AC too hard/brittle at low temperatures) –Fatigue cracking (AC ages and eventually “wears out”) Grade & Quality of AC determines resistance to failure Chemistry determines AC quality

6 Asphalt Cement - Penetration Asphalts originally “penetration graded” –Penetration at 25°C (77°F) “ambient temperature” –Softer (higher pen) - colder climates –Harder (lower pen) - hotter climates –85/100, 120/150, 200/ g penetration 0 sec 5 sec

7 Asphalt Cement - Viscosity Later, “Viscosity graded” Viscosity = Resistance to flow –Absolute Viscosity at 60°C (140°F) - Summer pavement temperature AC-20 = 2000 ±20% ( ) poise AC-10 = p AC-5 = p –Softer (lower viscosity) - colder climates vacuum

8 Performance Graded Asphalts –Performance at high and low temperatures –SHRP Super Pave PG (Performance Grades) –PG Grading system based on: Climate (Temperatures in ºC) Risk (Reliability Factor) Traffic speed and load (Grade “Bumping”) –PG day High Pavement Temp, 64 °C = 147 °F Single day Coldest Air Temp, -28°C = -18 °F


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