Suitability of static yield stress evolution to assess thixotropy of flowable cementitious materials

Abstract

Behavior of self-consolidating concrete (SCC) after casting (such as stability, formwork pressure, and multi-layer interfaces) is directly affected by the flocculation aspect of thixotropy. The main objective of this paper is to evaluate the suitability of static yield stress (τ0) evolution over time to assess the magnitude of thixotropy. Three series of highly flowable mortar mixtures were tested using the four-bladed vane method, and the results were compared with the cohesion (C) values obtained by direct shear. Test results have shown that τ0 and C responses determined at given resting time are quite close to each other, indicating an adequate correlation between thixotropy determined using vane and direct shear methods. This reflects the suitability of considering τ0 evolution over time to quantify the flocculation aspect of thixotropy, as well as its robustness as it is not affected by the testing method.