Sorptivity-Based Service Life Predictions for Concrete Pavements.
Sorptivity-Based Service Life Predictions for Concrete
Bentz, D. P.; Ehlen, M. A.; Ferraris, C. F.; Garboczi,
Concrete Pavements, 7th International Conference.
Proceedings. Volume 1. International Society for
Concrete Pavements. September 9-13, 2001, Orlando, FL,
181-193 pp, 2001.
concretes; degradation; service life; simulation;
The degradation of concrete pavements is often
controlled by the transport of a deleterious species
(chloride or sulfate ions, or water in the case of
freeze/thaw) into the concrete. With this in mind, a
three-year research project, funded by the Federal
Highway Administration, has culminated in the
development of sorptivity-based service life models for
concrete pavements and bridge decks. To develop a
service life model, one needs to identify and model the
suspected degradation mechanism, develop laboratory
tests to evaluate the critical material properties, and
adequately characterize the exposure environment. For
this project, degradation mechanisms for sulfate attack
(ettringite-induced expansion) and freeze/thaw
degradation (critical saturation of the air void system)
have been postulated. To evaluate sorptivity, a
laboratory-based testing protocol for conditioning and
assessing the sorption properties of field concrete
cores has been developed and submitted to ASTM committee
C09 for standardization. To characterize the exposure
environment, a one-dimensional finite difference
computer model which utilizes typical meteorological
year weather data supplied by the National Renewable
Energy Laboratory has been developed to predict the
concrete pavement surface temperature and
time-of-wetness history for a wide variety of
geographical locations thoughout the United States.
Finally, these methods and computational tools have been
integrated into a Windows-based computer software
package, CONCLIFE, which provides sorptivity-based
service life predictions.