Resumo A proteção passiva contra incêndio (PPCI) é um campo de estudo aplicado à indústria da construção civil. Os resíduos de tijolos refratários contêm elementos que podem contribuir para as propriedades necessárias à PPCI. Diante disso, o trabalho desenvolveu uma argamassa com resíduos de tijolos refratários para utilização como PPCI. As 4 formulações propostas tiveram a resistência à compressão e flexão, densidade e porosidade aparente, condutividade térmica e variação linear avaliadas antes e após tratamento térmico a 600 °C e a 1100 °C. A densidade não apresentou significativas diferenças entre as formulações. A porosidade aumentou após o tratamento térmico. A mistura que apresentou maior contração a 1100 °C foi aquela com maior teor de gesso e todas as demais apresentaram valores de contração menores que o máximo permitido pela C195. A proporção que utilizou maior quantidade de gesso foi o que obteve a menor condutividade térmica. Portanto, conclui-se que a utilização do resíduo refratário é viável para PPCI, uma vez que atendem aos requisitos normativos.

Abstract Passive fire protection (PFP) is a field of study applied to the civil construction industry. Refractory brick waste contains elements that can contribute to the properties necessary for PFP. Therefore, this study developed a mortar with refractory brick waste for use as PFP. The authors proposed four formulations with compressive and flexural strength, bulk density and apparent porosity, thermal conductivity, and linear variation that were evaluated before and after heat treatment at 600 °C and 1100 °C. The density did not show significant differences between the formulations. The porosity increased after the heat treatment. The mixture that showed the highest shrinkage at 1100 °C was the one with the highest gypsum content, and all the other ones had shrinkage values lower than the maximum allowed by the C195 standard. The mixture that used the highest amount of gypsum was the one that obtained the lowest thermal conductivity. Therefore, it is concluded that using refractory waste is viable for the development of PFP mortars because they meet the regulatory requirements.

The work presents the characterization of clays from sterile mining of the concentrated phosphatic materials of Araxá in Minas Gerais as pozzolanic materials. Three clays of distinct tones, namely, yellow (YC), red (RC), and intermediate (IC) clays, were used at different levels of excavation depth. The clays were calcined at three temperatures (680, 760, and 840 °C) in a muffle-type electric oven. The pozzolanic activity levels of the calcined clays was measured through the conductivity change in saturated Ca(OH)2 solutions and also from the result of the compressive failure load achieved by mortars with 35% of the Portland cement replaced with the calcined material. The results indicated that the calcined clays showed a high level of pozzolanic activity and can be used as a partial substitute for Portland cement, thus suggesting the possibility of recovering this sterile material.