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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]

In recent decades, geopolymer concrete has often been viewed as an alternative to traditional concrete. Although its comparatively lower production of greenhouse gas emissions during a lifecycle is usually mentioned at the top of the list of benefits, the possibility of using various waste materials in its production is a clear advantage as well. This literature review summarizes and analyses the existing information on the different available construction wastes for the production of geopolymer and foamed geopolymer concrete and analyzes the curing conditions, constituents in the aluminosilicate precursor, mechanical properties, and the activator type. As part of the literature review, the use of autoclaved aerated concrete and brick wastes has been evaluated. Autoclaved concrete has been chosen because it is a typical low-strength, cement-based construction material and demolition waste that is currently disposed of in landfills, making it quite a challenge for direct use as a supplementary cementitious material. On the other hand, brick waste, one of the most common construction wastes, can be feasibly used in the form of brick dust. This literature review uses data from randomly selected studies. [ABSTRACT FROM AUTHOR]

Foamed concrete has been used as a building material since the early 1920s. In the beginning, it was used as an insulation material with very low density. Since then there have been attempts to improve the structural properties in order to increase materials load-bearing capacity. In the present-day foamed concrete is being used in soil reinforcement, manufacturing of building blocks and other sorts of construction materials (Mugahed Amran, Farzadnia, & Abang Ali, 2015). The aim of this article is to determine the behaviour and long-term properties of foamed concrete. Cylindrical specimens (Ø46×190 mm) were used for creep and shrinkage testing. The creep properties of the specimens were determined by loading them with 20% and 60% of the ultimate compressive stress value (Sprince, 2015). The compressive strength, creep, shrinkage and specific creep of the material were examined. It was determined that during 90 days of creep testing the non-linear creep deformations (specimens loaded with 60% of the ultimate stress) are 4 times larger than linear creep deformations (specimens loaded with 20% of the ultimate stress). Also, changes in the modulus of elasticity of foamed concrete were researched over time. Foamed concrete modulus of elasticity reached 12.21 GPa on the 28th day, 12.49 GPa on the 62nd and 14.23 GPa on the 144th day since the specimens were made. [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]

The aim of this study was to experimentally investigate the creep behavior of developed concrete compositions in order to evaluate the possibility of using glass powder and small clay particles as active additives in concrete by replacing cement. Several concrete mixes were designed and prepared, then 160x40x40mm specimens of each batch were made and tested. The specimens were subjected to a uniform compression load kept constant over a long period of time in a constant room temperature and with a constant level of moisture. The specimens were hardened in two extreme environments: in one case there was 100% humidity provided by protecting the specimens from desiccation and in the other case the specimens were air-dried and protected from any moisture. The compression strength and modulus of elasticity of the developed concrete mixes were determined and compared with those of the reference concrete. [ABSTRACT FROM AUTHOR]