Abstract: Technological developments in construction have led to an increase in the use of 3D modelling using CAD environments. The popularity of this approach has increased in tandem with developments in industry branches which use 3D printers to print concrete based printing materials in construction, as these allow freedom in shaping the dimensions of supporting elements. One of the biggest challenges for researchers working on this highly innovative technology is that of cement material shrinkage. This article presents the findings of research on an original method of measuring deformations caused by shrinkage in 3D-printed concrete elements. It also discusses the results of tests on base mixes, as well as comparisons between the influence of internal and external curing methods on the development of deformations and their final outcomes. Furthermore, the article discusses differences between deformations formed after seven days of hardening without curing, with those which occur when two common, traditional concrete curing methods are used: foil insulation and shrinkage reducing admixtures. In addition, the article examines the effects of internal curing on the 1, 7, 14, 21 and 28 day mechanical properties of concrete, in accordance with EN 196-1 and EN 12390-2. Studies have shown that the optimal amount of shrinkage reducing admixtures is 4% (in relation to the mass of cement), resulting in a reduction in total shrinkage of 23%. The use of a shrinkage reducing admixture in 3D-printed concrete does not affect their strength after 28 days, but slows the strength development during the first 7 days.

Abstract: Com o advento de novas técnicas de Manufatura Aditiva foi possível à introdução de diversos metais como matéria prima e isso tem sido uma revolução para indústria, pois permite muitas possibilidades. Neste artigo serão apresentadas técnicas de impressão 3D em metais, as matérias primas metálicas mais utilizadas, os custos da manufatura aditiva comparando com a manufatura subtrativa. A utilização desta técnica na área aeronáutica e automotiva, além das dificuldades enfrentadas por esta técnica na fabricação de componentes que necessitam de grande resistência estrutural, e por fim, serão apresentadas possíveis aplicações no futuro próximo.

Abstract: Binder jet 3D printing of ceramic materials is an additive manufacturing technology that enables the production of complex and multi-functional parts through the selective jet binding of precursor powder beds. The present study makes use of the 3D Sand Printing (3DSP) process to create moulds and cores in the casting industry. The use of the 3DSP components as functional parts in industrial production is limited due to the uncertainty associated with their mechanical properties, such as their permeability and thermal stability. Moreover, because of the porous nature of their printed structures, their mechanical properties are dispersed and rather difficult to reproduce. This study aims to characterise the impact of different printing parameters on the mechanical performance of printed parts. For this purpose, a specific device was made in order to assess the mechanical characteristics of samples printed via this technique. The effects of processing parameters such as the printing orientation and building direction on the compressive properties of the printed specimens have also been carefully studied. Microstructural analyses were performed to better understand the relationship between the 3DSP process and the mechanical properties of the components produced from it. The results show that the mechanical tests carried out significantly improve the property reproducibility of the samples made using this technique.