Iowa Department of Transportation
Bridge decks; Chlorides; Coarse aggregates; High performance concrete; Permeability; Test procedures
The overall goal is to identify an effective test method to reduce uncertainty concerning the use of certain Iowa aggregate sources for manufacturing high performance concrete (HPC) for bridge decks. The research team's approach is to investigate typical Iowa HPC coarse aggregates and study the relationships between the aggregate properties, especially the pore system properties, and concrete permeability. The specific objectives of the proposed study include the following: (A) To examine the relationship between the coarse aggregate pore properties and concrete permeability/chloride ingress measured using different methods (e .g., natural chloride penetration and electrical methods); (B) To identify the properties (such as porosity, median pore throat diameter, etc.) that describe the main features of aggregate pore structure; (C) To critically evaluate test methods for quantifying key pore system properties of coarse aggregates effectively; and (D) To establish criteria for accepting Iowa coarse aggregates for the manufacture of low permeability HPC for Iowa bridge decks.