РЕОЛОГІЧНІ ВЛАСТИВОСТІ ЦЕМЕНТНИХ ПАСТ З ВВЕДЕННЯМ ДИСПЕРСНОЇ ФРАКЦІЇ БЕТОННОГО БРУХТУ

Abstract

This study focuses on the development and optimization of cement mixtures containing a dispersed fraction of concrete waste (concrete powder) as an active mineral additive for use in 3D printing technologies. The paper highlights the relevance of resource-efficient and environmentally sustainable solutions in modern construction by replacing a portion of Portland cement with secondary mineral components obtained from recycling construction waste. The article outlines the chemical and physicochemical mechanisms regulating the reactivity of concrete powder. Chemically, the hydration of residual unreacted cement grains and potential pozzolanic reactions on the surfaces of amorphous particles facilitate the formation of additional cement phases. Physicochemically, concrete powder act as crystallization centers according to the Gibbs-Volmer nucleation theory, accelerating structure formation and compacting the hardened matrix. Particular attention is paid to the rheological properties of modified cement pastes – viscosity and normal consistency, which determine the extrusion and stability of printed layers. The article presents the results of studies of the influence of concrete powders in combination with a superplasticizer and a water-retaining additive on the main rheological properties of cement pastes using methods of mathematical design of experiments.