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In recent years, 3D printing has been more and more used in the development of buildings and building elements. Mostly-printed structures are subjected to compression that is oriented perpendicular to the layer laying direction. When applying load in this way, the printed structure exhibits characteristics similar to masonry structures. However, as the technology and application of 3D printing develop, the structures also become more complicated and subjected not only to direct compression but other stresses as well. In this paper, long-term properties together with compressive strength were determined for 3D-printed specimens with load applied in the same direction as the layers are laid. The long-term and mechanical properties were compared with cast same-composition specimens. Results show that for the printed specimens, the compressive strength was more than two times lower than cast specimens, while the creep properties were slightly lower for the printed specimens. [ABSTRACT FROM AUTHOR]

The challenge of the present investigation is to evaluate the possibility of using micro- and nano- fillers as active additives in concrete composition for the replacement of cement and elaborating a new concrete. This paper examines experimental test results carried out with the aim to evaluate the long-term deformations - creep of elaborated concrete composition. Two kinds of fiber-reinforced high performance concrete mixes using those additives and a cocktail of polyvinyl alcohol (PVA) fibers have been developed and prepared. The cubes and cylindrical specimens were prepared for each composition and tested. Cylindrical specimens were put into a creep lever test stand and subjected to a uniform compressive load kept constant over a long period in constant room temperature and level of moisture. This study was carried out in two different extreme environments: in one case they were kept in 100% humidity ensured by preventing the desiccation of the concrete and in the other case samples were air-dried. Compressive strength and modulus of elasticity were determined for each concrete composition. The results of the experiments allow the authors to predict long-term deformations of the concrete. [ABSTRACT FROM AUTHOR]