A thixotropy model for fresh fluid concretes: Theory, validation and applications

In this paper, the methods used to measure and model thixotropy of fresh concrete in the civil engineering field are described and a simple thixotropy model is presented. It is shown that this model is in agreement with the experimental observations that can be found in the literature and a classification of SCC according to their flocculation rate Athix is proposed. The predictions of the model are compared with experimental measurements obtained with a concrete rheometer. In the last part, two applications of the model are briefly presented as examples (pressure formwork prediction and multi-layer casting of fluid concretes). It is shown that according to the element to be cast (slab or wall), a non-thixotropic SCC (low flocculation rate) or a highly thixotropic SCC (high flocculation rate) is respectively more adapted.