John E. Haddock, Ph.D., P.E.Associate ProfessorSchool of Civil EngineeringPurdue UniversityWest Lafayette, IN
Joseph Seidel, P.E. Graduate Research Assistant School of Civil Engineering
Bernie Tao, Ph.D. Professor School of Agricultural and Biological
Engineering
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• 94% of U.S. paved roads are paved with asphalt
• Refined from a nonrenewable resource
• Refining methods can make asphalt scarce and more expensive
• Enormous demand for maintenance applications
Time to examine renewable bio-alternatives as binding agents in flexible pavement systems.
Utilization Percent Replacement
Direct Alternative
100%
Asphalt Extender
25-75%
Asphalt Modifier
< 10%
Shell
Ecopave
E
Product Price (per lb)Asphalt $0.20-0.37Soybean Oil $0.56-0.69Soybean Soapstock
$0.13-0.25
SOAPSTOCK SUPPLY
• Availability will increase with increased commercial use of soybean oil and soy-based resins
• Estimated 0.5 million tons/yr produced
ASPHALT DEMAND
• World Demand for Asphalt in 2004 – about 110 million tons
• 85% toward paving products
• United States represented 36% of the world demand
Will it raise food prices? What about additional fuel and
fertilizer use? Since soapstock is a byproduct of soybean
oil processing, its utilization will not be an impetus for growth
Will it compete with existing/future markets? Protein source in animal feed (existing) Biodiesel (possibly)
Currently used as an environmentally friendly dust suppressant
Known for its biodegradability and low volatility
As a flexible binder material it will need to be evaluated using the standardized tests
WorkableStable (oxidation resistance)DurableFlexibleFatigue resistantTolerant to thermal changesResistant to moisture damage
Testing various material constituents using a statistical approach
The use of soybean soapstock as a pavement binder appears to be technically feasible
Current supply is not equivalent to demand, but could work in a regional approach
Appears to be a cost-effective alternative to asphalt binders
Currently is environmentally friendly Questions about possible environmental
damage from additional cultivation