Nonlinear model for early age creep of concrete under compression strains

- A viscoelastic-plastic creep model for early age concrete creep prediction was established.
- The acoustic emission test was conducted to identify any damage that might have occurred during creep.
- Experiment on the nonlinear creep of early-age concrete was carried out.

Creep of early age concrete is more significant than that of hardened concrete, and it is possible that early age concrete creep presents nonlinearly because of high stresses imposed during construction. In this paper, a viscoelastic-plastic model was proposed to simulate early age concrete creep. Experiments of early age creep of concrete under different stresses, have revealed the nonlinear features of specimens under high stresses. Acoustic emission (AE) technology was applied to collect damage information of early age concrete during creep, and the relationship between the degree of damage and increments of nonlinear creep was deduced according to test data. The parameters involved in the model were regressed. Also, a modified B3 model was proposed to consider nonlinear creep increments of concrete. It can be conclude that the item concerning concrete damage in the proposed model is important for predict the nonlinearity of early-age concrete creep, and it can be used to modify existing models.