Prediction of residual stress due to early age behaviour of massive concrete structures: on site experiments and macroscopic modelling

TL;DR

This paper presents a practical on-site method combining simple tests and macroscopic modeling to predict residual stresses and cracking risks in early age concrete structures, validated through experiments and finite element analysis.

Contribution

It introduces a straightforward approach using restrained shrinkage tests and a Kelvin visco-elastic model to identify early age creep parameters for concrete.

Findings

Good agreement between predicted and measured stress development.

Validated method for on-site residual stress prediction.

Effective identification of early age creep parameters.

Abstract

Early age behaviour of concrete is based on complex multi-physical and multiscale phenomena. The predication of both cracking risk and residual stresses in hardened concrete structures is still a challenging task. We propose in this paper a practical method to characterize in the construction site the material parameters and to identify a macroscopic model from simple tests. We propose for instance to use a restrained shrinkage ring test to identify a basic early age creep model based on a simple ageing visco-elastic Kelvin model. The strain data obtained from this test can be treated through an early age finite element incremental procedure such that the fitting parameters of the creep law can be quickly identified. The others properties of concrete have been measured at different ages (elastic properties, hydration kinetics, and coefficient of thermal expansion). From the identified early age model, we computed the temperature rise and the stress development in a non reinforced concrete stress for nuclear waste. The good agreement between in-situ measurement and predicted behaviour allowed us to validate our approach.