John E. Haddock, Ph.D., P.E. Associate Professor School of Civil Engineering Purdue University West Lafayette, IN

 Joseph Seidel, P.E. Graduate Research Assistant School of Civil Engineering  Bernie Tao, Ph.D. Professor School of Agricultural and Biological Engineering

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.

UtilizationPercent Replacement Direct Alternative100% Asphalt Extender25-75% Asphalt Modifier< 10%

Shell Ecopave E

ProductPrice (per lb) Asphalt$ Soybean Oil$ Soybean Soapstock$

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

 Workable  Stable (oxidation resistance)  Durable  Flexible  Fatigue resistant  Tolerant to thermal changes  Resistant to moisture damage

 Testing various material constituents using a statistical approach

▪ Literature review ▪ Investigate soy soapstock ▪ Analyze characteristics ▪ Determine necessary modifications ▪ Formulate & test binders ▪ Produce new paving binders ▪ Test HMA mixtures ▪ Analyze results

 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