Tensile Creep and Unloading Creep Recovery Testing of Dam Concrete with Fly Ash

Gradual creep recovery manifests when a concrete specimen that has been subjected to a sustained stress is unloaded. Although creep and creep recovery are important properties of concrete, there is little research on the tensile creep and creep recovery of dam concrete with fly ash due to the difficulties and long duration of tensile creep tests. Laboratory tests of tensile creep and unloading creep recovery are conducted using dam concrete with fly ash at different curing temperatures and loading times. Then, the tensile loading creep test data are used to determine the parameters of an eight-parameter tensile creep model based on a complex optimization method. Assuming that the tensile specific creep is equal and opposite to the compressive specific creep, the compressive specific creep corresponding to the unloading time is calculated by the tensile specific creep, and the theoretical curve of unloading creep recovery is obtained based on the superposition principle of elastic creep theory. The analysis results show that the theoretical curves of unloading creep recovery are close to the test curves.