Martinelli, Antonio EduardoDiniz, Hugo Alessandro Almeida2023-05-152023-05-152023-01-30DINIZ, Hugo Alessandro Almeida. Avaliação da influência da incorporação de metacaulim e das relações areia/ligantes e água/ligantes nas propriedades de concretos para impressão 3D. Orientador: Antônio Eduardo Martinelli. 2023. 131f. Tese (Doutorado em Ciência e Engenharia de Materiais) - Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Natal, 2023.https://repositorio.ufrn.br/handle/123456789/524233D printing of concrete (3DCP) is a construction technique based on the deposition of successive layers of a cementitious composite without the need for conventional formwork. To apply the technique, the composite must be able to pass through a printing nozzle and support the successive printed layers. This method promotes a faster execution and with less waste, however, there are few studies to understand these abilities. In this perspective, the objective of this study is to understand the influence of sand, water, and metakaolin incorporation on the extrusion capabilities and constructability of cementitious composites for 3D printing. The analysis was based on an experimental statistical planning of mixtures to gauge the effect and interaction of the variables: cement replacement content by metakaolin, sand/binder ratio and water/binder ratio. Ten mixtures were evaluated through the properties of extrudability, constructability, rheology and strength in the hardened state. To assist in the analysis, experimental flow and dimensional stability tests were developed. The water/binder factor had a preponderant influence on the extrudability, being the component responsible for the fluidization of the materials. The metakaolin reduced the extrusion capacity, and can be used as a control mechanism. However, the partial replacement of cement increased deformation by reducing thixotropy, being negative for constructability. The metakaolin also promoted optimization of the application time, by delaying the setting. The sand increased the constructability by increasing the cohesion between the particles, but reduced the application time by increasing the evaporation of the mixing water. There was a significant interaction between sand and metakaolin, caused by the reduction of packing, which influenced the increase of extrusion and reduction of the constructive capacity. It was also observed that the printing process and the deformations that occurred, influenced the final strength of the printed block. In the end, it was possible to understand the effect of each component, as well as, propose new tests and parameters: the sand/binder ratio 1: 1.5 proved to be feasible in all the properties analyzed; mixtures with 30% of metakaolin presented adequate constructability and extrusion at higher water contents; the water/binder factor below 0.37 proved to be unfeasible, preventing the printing of the M3 and M10 mixtures; the maximum yield stress to enable printing was 250 N; the minimum spread of 161 mm; and the ideal flow rate at 20 ml/s.Acesso AbertoEngenharia dos materiaisImpressão 3D de concreto - 3DCPCapacidade de extrusãoConstrutibilidadeMetacaulimPlanejamento de misturadoctoralThesisCNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA