Meso-scale analysis on the effect of coarse aggregate properties on the creep behaviors of concrete based on the 3D particle-based method

Coarse aggregate, as the main component of concrete, has a significant influence on its behaviors. In this work, a 3D particle-based method was utilized to investigate the effect of coarse aggregate properties on the creep behaviors of concrete at a meso-scale level, in which concrete was composed of mortar, coarse aggregate, and interfacial transition zone (ITZ). Firstly, cluster-based modules for aggregate were generated based on the real aggregate geometry obtained by 3D scanning, and then, the developed aggregates were randomly distributed in the model according to the specified aggregate gradation and content. Then, the Burger model, a linear viscoelastic-plastic model, was employed to define the contact mechanical characteristics of mortar and ITZ. Meanwhile, the linear parallel bond model, a linear elastic bonding interface with dimensions that can transmit forces and moments, was utilized to describe the contact bonds between balls in the aggregate. On this basis, the effects of coarse aggregate properties (i.e., surface topography, shape, gradation, content, and elastic modulus) on the concrete creep were studied quantitatively. The results show that the coarser the surface topography of aggregate, the smaller creep. Also, with the increase in the content or elastic modulus of coarse aggregate, concrete creep showed a decreasing trend. In addition, the constraint action of the aggregate can be illustrated by the displacement fields. Overall, the 3D particle-based proposed in this work can provide an effective tool to explain the creep behavior of concrete materials from the meso-scale.