Presentation on theme: "Warm-Mix Asphalt: A Window to a Better Road Phase 1 Hosin David Lee, P.E. Ph.D., Professor Public Policy Center, Department of Civil and Environmental."— Presentation transcript:
Warm-Mix Asphalt: A Window to a Better Road Phase 1 Hosin David Lee, P.E. Ph.D., Professor Public Policy Center, Department of Civil and Environmental Engineering, University of Iowa President of Korean-American Scientists and Engineers Association (KSEA)
Disclaimer The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the information presented herein. This document is disseminated under the sponsorship of the Department of Transportation University Transportation Centers Program, in the interest of information exchange. The U.S. Government assumes no liability for the contents or use thereof.
Too High Temperature of Asphalt Mix During the past century, the asphalt industry has been concerned about keeping the temperature of asphalt mix high enough for adequate coating, placement, and compaction. An answer to the problems in coating and compaction has been to raise the temperature of asphalt mix. Now, for better performance and the environment, a new approach is to lower the temperature of asphalt mix: Warm-Mix Asphalt (WMA), a window to the future.
Workers Exposure to Asphalt Fumes About 4,000 asphalt plants and 7,000 paving contractors employ nearly 300,000 workers in the United States. In 1977, the National Institute for Occupational Safety and Health (NIOSH) recommended that workers should not be exposed to airborne particulates at a concentration greater than 5mg/m 3 during any 15-minute period. NIOSH concluded that the collective data currently available from studies on paving asphalt provided insufficient evidence for an association between lung cancer and exposure to asphalt fumes during paving. Asphalt fumes and PAHs at the HMA job site were below the current acceptable exposure limits.
Exposure of Workers to Emissions Working at HMA and WMA Job Sites
Which Picture Represent WMA Construction Sites in Iowa?
WMA Plants Reduce Greenhouse Gas EAP (2006); Newcomb (2007); Ruhl (2004); DAngelo (2008) The U.S. Environmental Protection Agency (EPA) issued a rule that was designed to reduce SO 2 by 70% and NO x emissions by 60% by 2015. Some state and local governments require that HMA plants in some ozone sensitive areas limit asphalt production to a certain number of hours per week. WMA plants would reduce CO 2 and SO 2 by 30% to 40%, volatile organic compounds (VOC) by 50 percent, CO by 10% to 30%, NO x by 60% to 70% and dust by 20% to 25%.
WMA Saves Energy Cost Compared with HMA IcelandHonolulu, HIJoliet, IL Fuel sourceNo. 2 Fuel oilDieselNatural gas Fuel to make 1 ton of HMA 2-3 gallons 2.5-3.5 therms Fuel Cost$2.50/gal$2.20-3.20/gal$0.70-0.80/therm Fuel Cost to make 1 ton of HMA $5.00-$7.50$4.40-$9.00$1.75-$2.80 Electricity to make 1 ton of HMA 8-14 kWh Electricity Cost$0.02/kWh$0.1805/kWh$0.0445/kWh Average energy cost for 1 ton of HMA $5.15-$7.78$5.84-$11.53$2.11-$3.44 20% savings with WMA $1.00-$1.50$0.88-$1.80$0.35-$0.56 50% savings with WMA $2.50-$3.75$2.20-$4.50$0.88-$1.40 Ólöf Kristjánsdóttir (2007)
WMA Additives Selected for Laboratory Evaluation at the University of Iowa Organic Additives: CECABASE RT®, Sasobit® Foaming Additives: Asphalt-min®, Advera WMA Chemical Additives: Evotherm J1, Rediset TM WMX
Evaluation of WMA Products in Laboratory Indirect Tensile Strength Test Indirect Tensile Strength Test Moisture Sensitivity Test Moisture Sensitivity Test Dynamic Modulus Test Dynamic Modulus Test Repeated Load Test Repeated Load Test Temperature Maximum Specific Gravity Bulk Specific Gravity Air Void Six WMA Mixtures: CECABASE RT ®, Sasobit ®, Asphalt-min ®, Advera WMA, Evotherm J1, and Rediset TM WMX. Six WMA Mixtures: CECABASE RT ®, Sasobit ®, Asphalt-min ®, Advera WMA, Evotherm J1, and Rediset TM WMX. Control WMA Mixture and HMA Mixture
Mixing Method and Dosage Rate of WMA Additive AdditiveProcessDosage Rate CECABASE RT®Wet0.40% of binder weight Sasobit® Dry 1.50% of binder weight Wet Asphalt-min®Dry0.30% of mixture weight Advera WMA®Dry0.25% of mixture weight Evotherm J1®Wet0.50% of binder weight Rediset TM WMXWet2.00% of binder weight
Mix Design Parameters Aggregates Nominal Maximum Aggregate Size of 19.0 mm N design 86 gyrations (for 3 million ESAL) Asphalt Content5.5% using PG 64-34 Aggregate Heating Temp. 125°C for WMA 135°C for HMA Asphalt Heating Temp. 149°C for both WMA and HMA
Mixing and Compaction Temperatures of WMA Mixtures
Ranking of ITS, TSR, Dynamic Modulus, and Flow Number of WMA Mixtures Type of Mix Ranking Average Ranking Score Indirect Tensile Strength Tensile Strength Ratio Dynamic Modulus Flow Number CECABASE RT® 95987.75 Sasobit® (wet process) 36123 Sasobit® (dry process) 44212.75 Aspha-min® (powder) 109--9.5 Aspha-min® (granular) 78777.25 Advera WMA 810598 Evotherm J1 12663.75 Rediset TM WMX 23353.25 Control WMA 57846 Control HMA 61433.5
Summary and Conclusions Based on the limited test results, Sasobit®, Evotherm J1, and RedisetTM WMX additives are effective in producing WMA mixtures in the laboratory that are comparable to HMA mixtures. Pavement is expected to perform better because the asphalt is not aged. Working environment will be better for construction workers with a lower amount of asphalt fumes. In the future, the majority of asphalt mixtures will be produced at a lower temperature than today.
Future Research Lime and Anti-stripping Additives should be considered for WMA to improve the moisture susceptibility. To predict the rutting performance under moisture, Hamburg Wheel Tracking test should be performed. More test sections using WMA should be constructed adjacent to HMA.
Cool-Mix Asphalt: A Door to a Better Road Phase 2
Questions How to evaluate WMA for implementation? Why should WMA be used instead of HMA? How can WMA be adopted quickly in practice?