Strength Prediction of Mine Shaft Concrete Liner Cured under Freezing Condition
Exposure of concrete to cold temperature slows down the concrete hydration process and strength development. Some studies indicate that the concrete hydration process stops below -10°C, ending the strength development of the concrete. Standard practice recommends that concrete placed in cold temperature shall be protected against freezing until it attains a compressive strength of at least 3.5 MPa.
In a mine shaft construction, which often takes place under freezing condition, it is of interest to predict the strength developed in the concrete lining that is unprotected and exposed to the freezing condition. This paper presents a method to predict the strength development of the concrete when it is subject to freezing temperature. The method employs heat transfer analysis to estimate the temperature of the concrete at any given time. Concrete maturity concept is then used to relate the temperature and age of the concrete to the strength developed in the concrete. Various concrete properties related to the time-dependant thermal properties, as well as the heat generated by the hydration process, are also considered in the model.