The project developed a manual that provides step-by-step procedures for assessing the condition of corrosion-damaged bridge elements. The manual also includes procedures that can be used to estimate the expected remaining life of reinforced concrete bridge superstructure elements, and to determine the effects of maintenance and repair options on their service life.

Corrosion-induced deterioration of reinforced concrete bridge superstructure elements is a common and costly problem in the United States. A rational decision regarding maintenance, repair, or replacement of such deteriorated elements must take into account the condition of the element, the extent of deterioration, the expected remaining service life, and the impact of alternative maintenance and repair options on the service life of such elements. However, available publications do not provide reliable procedures for evaluating the existing condition of corrosion-damaged elements or approaches for comparing the effectiveness of maintenance and repair alternatives. Without such information, the selection of the optimum repair strategy cannot be ensured, leading to the application of a less desirable and often more costly repair strategy. Thus, research was needed to identify suitable procedures for assessing the condition of corrosion-damaged bridge elements, estimating the expected remaining service life of such elements, and determining the effects of maintenance and repair options on their service life.

Research developed a protocol for condition assessment of reinforced concrete bridge superstructure elements; a model for corrosion initiation for use in projecting future damage; and a model for estimating expected remaining service life that incorporated the concept of Susceptibility Index--an approach for interpreting the distribution of chloride ions in the concrete. The remaining service-life estimation process is presented as computational software in the form of a Visual Basic driven Excel spreadsheet to facilitate use. The research included tests on three bridges to obtain data for use in modeling the corrosion process and in validating the model's ability to project future deterioration, and provided guidance on the service life that may be attainable with different corrosion control, repair, and rehabilitation techniques. Finally, the research organized relevant information in the form of a manual to facilitate use by practitioners. The final report has been received; copies have been distributed to sponsors (state departments of Transportation), FHWA, and AASHTO.

The manual has been published as NCHRP Report 558.

NCHRP Web-Only Document 88 contains the data used in the development and validation of the service life model described in NCHRP Report 558. 

The computational software (Excel spreadsheet) for the service life estimation process developed in the project and a revised version compatible with Microsoft Office 2013 are also available.