Micromechanical modeling on autogenous and drying shrinkages of concrete

A micromechanical model for autogenous and drying shrinkage predictions of concrete at early-age is developed. The model is based on the capillary tension created in capillary pores in concrete and uses the interior humidity (RH) that can relate to the moisture loss in concrete directly as driving parameter for shrinkage predictions. The developed model can be used for shrinkage prediction of concrete, whatever the shrinkage is caused by self-desiccation or by dying. In addition, because the model can reflect the effect on moisture loss of age and position from one parameter, RH, the model can predict shrinkage strain in concrete structures not only for different time but also for different positions. To verify the model, a series shrinkage tests on three types of concrete with compressive strength around 30 MPa, 50 MPa and 80 MPa respectively at 28 days of moisture curing were carried out. The model predictions on the development of shrinkage strain are compared with experimental results and a good agreement between them is found.