3D-Concreting – Compositions, Techniques and Properties of Mixtures

Abstract

The paper reflects the problems of 3D-concreting technology, which is developing quite intensively in modern conditions of construction production. The most important condition for its practical implementation is the development of concrete mixture compositions that provide the necessary rheological (technological) properties for formation of products, elements of building structures or the structure as a whole, as well as providing the required pace of work and physical and mechanical characteristics and properties of the hardened concrete. At the initial stage of research carried out in the Research and Testing Laboratory of Concrete and Building Materials of the Belarusian National Technical University a number of concrete mixtures compositions were developed that are designed and provide the necessary conditions for the implementation of 3D-concreting of self-supporting and load-bearing structural elements respectively, in the manufacture of products of small architectural forms and the erection (arrangement) of building structures for various purposes. A methodology has been developed and implemented for the selection of a rational granulometric composition of aggregate, type, properties and amount of binder, chemical and mineral additives, together providing the required technological properties of concrete mixtures after they have been mixed with water. Original methods for assessing the rheological properties of water-soluble concrete mixtures and their changes over time, leading to an increase in the plastic strength of molded concrete, as well as a method for calculating the rate of concrete work depending on the properties of the concrete mixtures used, are proposed and experimentally substantiated. As a result, prerequisites have been created for further expansion of a number of compositions of dry concrete mixes taking into account their purpose for 3D-concreting, and for developing methods and evaluating the physical and mechanical characteristics and properties of hardened concrete, taking into consideration the purpose of manufactured products and erected (arranged) building structures.