Estimating early-age in situ strength development of concrete slabs

Post-tensioned concrete members are becoming very popular around the world due to structural efficiencies. However, some important issues related to concrete properties are not resolved yet. A more accurate prediction of the in situ early-age strength is needed to allow for the application of the post-tensioning (PT) load without causing any damage to the PT anchorage zone concrete. Strength–maturity functions are conventionally used to estimate the in situ concrete strength on the basis of a datum temperature. Temperature Match Curing (TMC) is an alternative method which provides a more representative estimate of the in situ strength. In this paper, the prediction of in situ strength of slabs using maturity functions is compared with the results from the TMC and those cured following standard recommendations. The comparisons generally reveal that the specimens cured and tested according to the standard methods can be used for estimating the strength development of concrete with some reservations.

▸ Prediction of in situ strength of suspended post-tensioned slabs is made using different methods. ▸ Temperature match, standard method of testing and prediction using maturity methods are compared. ▸ Study shows that standard methods can be used for estimating the strength development of concrete. ▸ The research findings are valid for average in situ temperature variation between 15 and 35 °C.