An experimental study was conducted to investigate the potential use of phosphogypsum (PG) to produce self-leveling underlayments. The study was designed in two stages. Initially a phosphoanhydrite (PA) was produced by heating phosphogypsum at temperatures of 350 °C, 450 °C, 550 °C, and 650 °C. Two periods of heating were applied (2 and 4 h). The formation of anhydrite was determined by thermogravimetric analysis (DTA-TG) and confirmed by X-ray diffraction (XRD). The results show that anhydrite II was obtained at temperatures above 450 °C, and at higher calcination temperatures the PA solubility was lower. In the second stage of this research, the PA was used in self-leveling underlayments as the main binder in the ternary system comprised of calcium sulfate, calcium aluminate cement, and Portland cement. Self-leveling mortar screeds produced using PA (550 °C/4 h) and PA (650 °C/4 h) showed the best performance in terms of mechanical strength and no degradation was observed after immersion and immersion-drying tests. The formation of ettringite, identified by scanning electron microscopy (SEM), may have contributed to these results. Morphological changes were studied using the scanning electron microscopy (SEM) technique.

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Os resíduos de construção e demolição (RCDs) são constituídos, em grande parte, por materiais de construção; entretanto, podem conter substâncias perigosas, tais como metais pesados. Tentando minimizar o volume dos RCDs a ser disposto em aterros sanitários, há tendência ao seu beneficiamento como agregados reciclados para utilização em materiais. Dessa forma, é imprescindível examinar os agregados, verificando o possível risco de contaminação ambiental e a interferência dos contaminantes em suas características. No estudo, utilizaramse agregados reciclados para produzir argamassas, que foram curadas por 28 dias e, posteriormente, encaminhadas ao ensaio de tanque, conforme NEN 7345. Os resultados mostram que metais pesados são lixiviados das argamassas produzidas com agregados reciclados em altas concentrações. Embora as concentrações obtidas em 24 horas sejam inferiores aos limites recomendados pela NBR 10004 (2004), são muito superiores aos preconizados pela diretiva européia 98/83/EC sobre qualidade de água para consumo humano.

The development of printers and materials for 3D Printing Construction during the last two decades has allowed the construction of increasingly complex projects. Some of them have broken construction speed records due to the simplification of the construction process, particularly in non-standard geometries. However, for performance and security reasons the materials used had considerable amounts of Portland cement (PC), a constituent that increases the cost and environmental impact of 3D Printable Materials (3DPM). Supplementary Cement Materials (SCM), such as fly ash, silica fume and metakaolin, have been considered a good solution to partially replace PC. This work aims to study the inclusion of limestone filler, fly ash and metakaolin as SCM in 3DPM. Firstly, a brief literature review was made to understand how these SCM can improve the materials’ 3DP capacity, and which methods are used to evaluate them. Based on the literature review, a laboratory methodology is proposed to assess 3DP properties, where tests such as slump and flow table are suggested. The influence of each SCM is evaluated by performing all tests on mortars with different dosages of each SCM. Finally, a mechanical extruder is used to extrude the developed mortars, which allowed us to compare the results of slump and flow table tests with the quality of extruded samples.

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