About the research
This project will continue collaborative research between geologists and engineers at Iowa State University and the Iowa Department of Transportation (DOT) into the evolution of pore networks in extremely long-lived Iowa concrete pavements. The results of a preliminary study of three concretes showed that the deterioration of coarse aggregates created an air void system in pavements before air entrainment was practiced. For this project, the team will:
- Make thin sections of the concretes to examine deteriorating coarse aggregate particles and determine their lithology and mode of deterioration.
- Computed tomography (CT) scan the remaining samples of concrete obtained in an earlier study (Hanson 2007) that represent a spectrum of ages and methods for pavement manufacture from Iowa. These samples will also be thin sectioned and the state of their coarse aggregate particles will be evaluated.
- Provide the DOT with a computer code that provides similar metrics to the RapidAir 457 Air Void Analyzer but for CT images (e.g., spacing factor, specific surface, number of voids, void size distribution).
By better understanding the evolution of the air void network and coarse aggregates in portland cement concrete (PCC), Iowa DOT pavement engineers and materials geologists will be able to make more informed decisions about designing pavements to ensure maximum longevity and durability. Thus, reducing life cycle costs of pavements to Iowa taxpayers.