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Alkali‐silica reaction continues to be a challenging durability issue for portland cement‐based concrete. While myriad of preventive options is known to reduce the risk of ASR, changes in availability and consistency of materials make either prescriptive or performance‐based approaches difficult to develop and then quickly adapt. In general, the research community has supported industry with practical solutions based on empirically derived relationships, mostly from accelerated test methods and to a lesser extent realistic exposure/field structures. It is time to increase the level of science behind our approach. The research team represented in this talk is investigating a new methodology that combines the alkali availability needed to initiate ASR (aggregate specific) with the available alkali from the total cementitious blend. The relationship between reactivity of a supplementary cementitious material and the ASR expansion is also explored. This keynote lecture will: 1) Explore performance‐based testing versus prescriptive approaches and why a hybrid approach should be considered ASR prevention; 2) Evaluate the relationship between accelerated laboratory tests, outdoor exposure blocks and field structures; 3) Examine the use of "non‐traditional" supplementary cementitious materials and/or chemical admixtures to prevent alkali‐silica reaction; 4) Propose future research needs and; 5) Make recommendations for how best to prevent alkali‐silica reactivity following the proposed approach. [ABSTRACT FROM AUTHOR]

This paper presents an investigation of five corrosion‐monitoring techniques for reinforced concrete. The techniques studied are the potentiodynamic, galvanostatic, and coulostatic direct‐current techniques as well as electrochemical impedance spectroscopy (EIS), and the connectionless electrical pulse response analysis (CEPRA) technique. The study included monitoring corrosion rates on reinforced concrete specimens with a range of admixed chloride percentages, cover depths, and rebar diameters for 8 months. After this period, the rebars were extracted for mass loss measurements to determine the average corrosion rates. EIS was found to provide accurate measurements of active and passive corrosion rates with a simplified spectrum‐analysis procedure. Galvanostatic and potentiodynamic techniques were able to measure the corrosion rates for actively corroding reinforcements accurately, while the coulostatic technique overestimated it. For passive reinforcements, the coulostatic technique provided reliable corrosion rate estimates, while the potentiodynamic technique provided a minor overestimation, due to the fast scan rate used, and the galvanostatic technique failed in detecting passivity, due to the short measurement duration and confinement failure. Finally, the CEPRA technique provided accurate corrosion rate predictions except for passive rebars with small diameters embedded in saturated concrete. The reliability of five corrosion‐monitoring techniques is evaluated through comparing the electrochemically determined corrosion rate to that found gravimetrically. It was found that reinforced concrete characteristics and test setup can have a significant impact on the accuracy of the techniques. The differences between the techniques, sources of error, and optimum test parameters are discussed in detail. [ABSTRACT FROM AUTHOR]