The support of the State of Iowa, the Portland Cement Association, and the National Institute of Standards and Technology is acknowledged. The assistance of Dr. Steven Forester and Marcia Simon of the Turner-Fairbanks Research Laboratory of the Federal Highway Administration, who provided access to their air void analysis system, is gratefully appreciated. The assistance of Vernon Marks and the Iowa Department of Transportation during the field study and collection of the cores was appreciated. The assistance of the reviewers, James Clifton, Clarissa Ferraris, and Steve Lane is appreciated.
The contents of this report reflect the views of the author, who is responsible for the facts and accuracy of the data presented. The contents do not necessarily reflect the views of Iowa DOT or the Portland Cement Association.