Effects of Atmospheric and Construction Conditions on Concrete Equivalent Ages

Concrete maturity, often indicated by its equivalent age, is determined by the interaction of temperature-dependent exothermic hydration reactions and the atmospheric conditions and curing regimen experienced during early ages. While indexes of concrete maturity have gained wide acceptance in determining proper opening times of structures and in investigations of structural failure, there is a need for a study showing how maturity in a given structure may change depending on environmental conditions experienced. In this paper, the SUNY Local Atmosphere Bridge Simulation model is used to predict the equivalent ages of New York State Department of Transportations Class HP concrete bridge decks for a variety of atmospheric and construction conditions. After 24 hrs of hydration, equivalent ages of the same bridge deck can vary from 10 to over 60 hrs depending on conditions when averaged over the deck thickness. They also can vary by more than 20 hrs through the slab thickness. In cases of self-desiccation, the maturity method may give misleading results.