Abstract
The applicability of the maturity method for prediction of the resistance of concrete to chloride ion penetration as measured by the ASTM C1202 Rapid Chloride Permeability Test was examined. Predictive capability of the method was successfully validated for laboratory-made, continuously moist cured ternary concrete containing 20% fly ash and 5% silica fume and was found to be excellent. Applicability of the developed maturity method was also verified for field-made and field-exposed ternary concrete used during a two-phase construction of a pilot high-performance concrete bridge deck in Indiana. Although agreement between the predicted and measured coulomb values was good for Phase 2 (constructed in spring), the rapid chloride permeability (RCP) values for Phase 1 (constructed in late fall) were consistently underestimated. Reasons for these disparities were thoroughly investigated. It was concluded that the measured values were higher than the predicted ones mainly because of the reduced degree of cement hydration and the potential increase in the water-to-cementitious materials ratio of concrete. Finally, two additional applications of the developed maturity method were demonstrated. The first application enables prediction of RCP values of concrete subjected to an accelerated curing procedure. This result may prove particularly useful for quality control, as 56-day RCP values may be obtained in about 13 days if temperature is elevated to 38°C. The second application allows for estimation of RCP values at a predefined age of first exposure to deicing salts as a function of construction date (assuming certain temperature history).
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