Experimental validation of a framework for hygro-mechanical simulation of self-induced stresses in concrete

An accurate simulation of the internal stresses that develop in concrete structures in service demands the explicit consideration of the internal heat and moisture movements that induce strains, which in turn have the potential to cause relevant internal stresses. Following a previous exploratory work from the authors, in which a thermo-hygro-mechanical simulation framework had been proposed, the present paper focuses on the validation of the proposed methodology through an experimental program targeted to assist prediction of the evolution of bulk drying shrinkage (and the corresponding internal stresses) in three specimens of different sizes. This paper presents the entire experimental program, which involved extensive concrete characterization using three distinct sizes of specimens, namely: moisture diffusion with internal humidity sensors, compressive strength, E-modulus, creep and shrinkage on three distinct specimen sizes. The program also included characterization of cement paste shrinkage, which was accomplished employing a newly proposed methodology based on the use of very thin specimens monitored with a handheld microscope. Finally, the obtained experimental data was used for partial validation of predictive capacities of the above mentioned simulation framework, mostly in regard to the prediction of bulk shrinkage. It is noted that the validation does not focus on thermal modelling, since this is a matter that has been addressed by the authors in previous works.