Thixotropic polymercement concrete: modeling, research, application

The article describes methods currently used to measure the thixotropic properties of concrete. It represents the theoretical substantiation of the thixotropy process from the point of view of colloidal chemistry with the usage of the potential energy curve of interaction between particles. The choice of the mathematical model for the approximation of experimental results has been justified. The works deals with the simplest and most adequate thixotropy model of polymercement concrete (PC-concrete) for construction printing and self-compacting cast concrete (SCC). The Russel’s model is consistent with the results of other researchers of cement concrete mixtures, which can be found in the literature, and with the proposed classification of concrete by the flocculation rate Athix. The rheological regularities for highly concentrated polymercement dispersions experimentally received on the laboratory rheometer “Reotest 2.1” are matched with the predictions of the thixotropic model. The author of the article describes the possibility of this model usage for layer-by-layer concrete application when using additive technologies. It is shown that non-thixotropic concrete can be used for cast self-compacting concrete elements (low flocculation rate), but construction printing requires only thixotropic or highly thixotropic concrete (high flocculation speed). Polymercement concrete P/C = 0.1 is demonstrated as the most adapted material for using in construction additive technologies. The achievement of the required properties is due to the increase in thixotropic properties with simultaneous increase in adhesion between layers.