WALAA S. MOGAWER, ALEXANDER J. AUSTERMAN, EMAD KASSEM, EYAD MASAD
Warm Mix Asphalt (WMA) mixtures are produced and placed at significantly lower temperatures than conventional Hot Mix Asphalt (HMA) mixtures. WMA mixtures can be produced by means of various technologies such as foaming (moisture-based) agents, wax-based additives, emulsionbased products, and surfactants. The lower temperatures provide several benefits such as reduced emissions and odors, decreased energy consumption for production, and improved environmental working conditions at plants and paving sites.
A concern that arises from the use of WMA technologies is the effect of lower production and placement temperatures on the moisture susceptibility of asphalt mixtures. This concern is primarily based on the fact that lower temperatures could lead to the possibility of inadequate drying of aggregates.
Furthermore, some WMA technologies introduce water into the mixture to increase its workability. Aggregates that are not sufficiently dried and/or the introduction of water into the mixture can adversely impact the adhesion between the aggregates and the asphalt binder and the cohesion of the mixture.
Adhesion and cohesion failures can lead to moisture damage.
This study consisted of two parts. The objective of the first part was to conduct an internet survey of materials and construction engineers in each of the fifty state Department of Transportation (DOT) agencies to determine if moisture damage related distresses have occurred in WMA field projects placed in the United States. Based on the responses received there was no evidence of moisture damage related distresses in the field.
_________________________________ 1Professor, University of Massachusetts Dartmouth & Director, Highway Sustainability Research Center 2Research Engineer, University of Massachusetts Dartmouth Highway Sustainability Research Center 3Assistant Research Engineer, Texas Transportation Institute, Texas A&M University 4Professor, Texas A&M University The oral presentation was made by Professor Mogawer.
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