Concrete Maturity Method Using Variable Temperature Curing for Normal and High-Strength Concrete. I: Experimental Study

The maturity method is used to estimate the effects of time and temperature on the strength development of concrete. This paper shows how variable curing temperatures affect strength development for both normal and high-strength concrete using the maturity concept. Experimental results for normal-strength concrete clearly show the crossover effect of strength development as the time-of-peak temperature varied. However, this crossover effect did not exist after actual ages were converted to the temperature-dependent equivalent age. In other words, the existing maturity method does not include the effect of varying the time-to-peak temperatures but instead includes the effect of the magnitude-of-peak temperatures. This fact for normal-strength concrete coincides with the American Society of Testing Materials stated limitation that the existing maturity method does not take into account the effect of early age temperature on long-term ultimate strength. For high-strength concrete, the results were inconclusive. The results of this $3\text{-}\text{year}$ study are used as a basis for an improved concrete maturity function called the modified maturity function.