Affiliation:
1. Kazan State University of Architecture and Engineering
Abstract
3D concrete printing (3DCP) is an innovative and promising method for constructing buildings and structures. Compositions of fine-grained concrete based on Portland cement are widely used as raw material mixtures in this technology. An alternative to the use of cement binder is the use of gypsum-cement-pozzolan binder, which can significantly reduce the cost of the finished product and, accordingly, increase its competitiveness. The raw material mixtures based on gypsum-cement-pozzolan binder presented on the construction market do not fully meet the requirements of 3DCP. Achieving optimal performance of gypsum-cement-pozzolan mixtures in 3DCP is possible by regulating the content of fine aggregate in the composition of fine-grained concrete, as well as the use of multicomponent modifying additives. The purpose of this work is to develop modified gypsum-cement-pozzolan concretes for 3DCP based on optimization of aggregate content and multifunctional additive, providing optimal rheotechnological properties of raw mixtures and technological characteristics of finished products. The formation of samples during experimental studies was carried out using the layer-by-layer extrusion method on a workshop construction 3D printer “AMT S-6044”. Modified gypsum-cement-pozzolan concretes have been developed for 3DCP with increased ultimate shear stress of the mixture (87.6 Pa), dimensional stability (23 cm), average composite density (1920 g/m3), flexural strength (8.4 MPa) and compression (30.6 MPa) and water resistance (0.85). The possibility of targeted regulation of the structure and properties of gypsum-cement-pozzolan mixtures and concrete due to the synergistic effect of the components of the developed multifunctional complex additive, including an aqueous solution of a polycarboxylate ether, a copolymer based on carboxylic acid esters, and a homogeneous mixture of oligoethoxysiloxanes, has been proven. The results obtained are consistent with the results of the differential thermal analysis of modified gypsum-cement-pozzolanic stone.