Influence of Curing Conditions on Strength Development and Strength Predictive Capability of Maturity Method

Abstract

Applicability of the maturity method to ternary systems with fly ash (FA) and silica fume (SF) has been investigated through laboratory and field studies. The laboratory study explored the impact of the combined effect of initial curing conditions and mixture composition on the compressive strength development and strength predictive capability of the maturity method. It was demonstrated that the maturity method can be used effectively to predict compressive strength of ternary concrete containing ordinary portland cement, FA, and SF. However, the accuracy of this method was strongly influenced by the amount of moisture supplied during early stages of curing and to a lesser extent by relative amounts of FA and SF in the mixture. Further (intermittent) moist curing of field trial batch (FTB) concrete (potentially simulating natural precipitation) was found to have a beneficial effect on strength development and, consequently, on the accuracy of strength prediction using the maturity method. Thus, even an occasional supply of moisture to high-performance concrete (especially at early age) may significantly minimize potential strength losses. Finally, applicability of the maturity method to ternary bridge deck concrete made and placed under field conditions and exposed to ambient temperature variations was verified. The predicted strength of bridge deck concrete was found to be approximately 10 MPa lower than the actual strength, irrespective of age. However, a correction factor was established to account for different air content in field concrete (compared with FTB concrete that was used for development of maturity function), which resulted in much more accurate strength estimates.