Concrete Durability: Linking Material Properties and Field Performance

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Concrete is the most widely-used construction material in the world but is often poorly understood and inadequately designed leading to premature deterioration in many aggressive exposure conditions. The applicant's research program is aimed at developing a fundamental understanding of the deterioration processes that can occur in different environments, determining the appropriate material properties to resist the destructive forces, quantifying and predicting rates of deterioration, and validating experimental observations with field performance studies. The main focus of the ongoing research program is to continue the development and improvement of appropriate test methods and predictive models for evaluating concrete's resistance to some of the more prevalent forms of deterioration; these are: (i) chloride ingress and corrosion of steel, (ii) alkali-silica reaction, (iii) sulfate attack, and (iv) combined ASR and freeze-thaw. The main objectives of the research program are: ***1. Validation of existing models for predicting chloride penetration, including models developed by the applicant and various collaborators. Validation will be conducted through ongoing long-term laboratory and field-exposure testing, and sampling of structures. A two-phase model will be developed to include the impact of carbonation as it penetrates from the surface. ***2. Development of improved test methods for alkali-silica reaction (ASR) with exposure conditions designed to provide sufficient moisture without allowing the ingress or egress of alkalis from the concrete. Validation and calibration will be performed using data from numerous long-term exposure sites that have been established by the applicant and collaborators, and through the use of data from existing structures that have been monitored for decades. ***3. Synergy between ASR and freeze-thaw attack. ASR results in expansion and cracking of concrete which may not in itself result in the end of the life of a structure but which may render it more vulnerable to other processes. Concretes with a range of ASR-damage levels and various degrees of saturation will be exposed to freeze-thaw cycles. This component of the research program (ASR-freeze/thaw) will conducted in collaboration with Jason Weiss of Oregon State University (previously with Purdue University). ***4. Development of an improved test for evaluating sulfate resistance of concrete. The test will be benchmarked using data from a sulfate exposure site. **