Materials Properties Model of Aging Concrete

A database model of aging concrete was developed to identify the changes in materials properties over time for Bureau of Reclamation (Reclamation) mass concrete dams. Materials properties data on mass concrete were input to the Reclamation Aging Concrete Information System (ACIS). The data were analyzed for trends in the deterioration of concretes subject to aging, including alkali aggregate reaction (AAR) and general aging of early twentieth century concrete with high water-tocement ratios. The aging concretes were compared to dams of similar age, but not suffering from aging processes. The aging concretes were also compared to known good quality concretes that were manufactured after about 1948 to specifically resist deterioration from AAR, freezing and thawing (FT), and sulfate attack. Trends were established for comparing the compressive strength, splitting and direct tensile strength, and elastic properties of aging and non-aging dams. The strength and elastic properties of aging mass concrete differed significantly from those of comparable non-aging concretes. Both spatial variations within a structure and long-term changes in strength and elastic properties were identified. The ACIS database can be used to track the long-term materials properties behavior of dams through comprehensive concrete coring and testing programs. Laboratory core test data are included for dams ranging from about 10 to more then 83 years old. These data provide the necessary supporting documentation for the Dam Safety Office Comprehensive Facilities Review evaluation process and for dams in need of corrective action.