DRYING CREEP OF CONCRETE - CONSTITUTIVE MODEL AND NEW EXPERIMENTS SEPARATING ITS MECHANISMS

A new experimental method which allows the direct separation of the co mponents of drying creep due to microcracking and stress-induced shrin kage is developed, demonstrated and validated. The basic idea is to co mpare the curvature creep of beams subjected to the same bending momen t but very different axial forces. The results confirm that drying cre ep has two different sources: microcracking and stress-induced shrinka ge. The latter increases continuously, whereas the former first increa ses and then decreases. The test results are fitted using a finite ele ment model. The results validate the present model for drying creep. T he microcracking is described by an established model, and the free (u nrestrained) shrinkage of a material element is shown to depend approx imately linearly on the humidity drop.