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