Application of maturity method to slipforming operations: Performance validation

During the last decades, the maturity method has been developed and used as one of the most favorable methods for estimating in-place concrete strength. Various maturity functions are considered in this study and their performance is compared based on the prediction of initial setting time using laboratory and field data of wide range of concrete mixtures to identify most suitable functions to be applied in slipforming operations. It is found that Freiesleben Hansen and Pederson (FHP) and Carino and Tank (CT) functions are better in predicting setting times compared to other functions. The apparent activation energy and temperature sensitivity factor associated with FHP and CT maturity functions are not influenced by varying the retarder dosage; or changing the method of setting time measurement. On the other hand, performance of maturity functions depends on the method of measuring setting time. In the current study two methods of setting time measurement are considered: the penetration resistance (PR) method as per ASTM C 403, and the 2 °C temperature (2C) increase method illustrated later. It is also confirmed that CT maturity functions can be used effectively with either the PR or the 2C methods in slipforming operations. However, CT function with PR (CT-PR) is found to be most suitable for predicting mock-up times for slipform when compared to those estimated from hard front generated by the rod method.