Modelling service life and life-cycle cost of steel-reinforced concrete:

The NIST / ACI / ASTM workshop on "Modelling Service Life and Life-Cycle Cost of Steel-Reinforced Concrete" was focused on possibilities for developing and standardizing such models, specifically for chloride-exposed concrete. The report includes summaries of nine presentations by model developers and reports from working groups that addressed i) chloride transport mechanisms and test methods, ii) chloride thresholds for corrosion initiation, iii) corrosion rate and time to rehabilitate or replace, and iv) life-cycle cost and service life prediction models. Several models for chloride transport to the steel were well advanced, but modelling ofchloride thresholds and corrosion rates poses difficulties that still need to be overcome. Economic models for life-cycle costing are in place and ready to use with service life models as they are developed. It was agreed that standard models for service life prediction and life-cycle costing are necessary. It was recommended that a simple, but useful model could and should be developed and standardized in the short tenn, with a more scientifically sound model being a longer term objective. The model development would need to be supported by development of some new standard test methods and databases containing appropriate and reliable data. Standardization of the models would be expected to be carried out in ACI committees and standardization of test methods in ASTM. NIST's Partnership for High-Performance Concrete Technology would contribute to the development ofmodels, test methods, and data.