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Comportamento do betão com incorporação de terra diatomácea residual a altas temperaturas
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Abstract(s)
O setor da construção civil, ao desempenhar seu papel essencial na provisão de habitações e infraestruturas, enfrenta o desafio de reduzir os impactos ambientais decorrentes de suas atividades. Nesse contexto, destacam-se pesquisas voltadas à incorporação de resíduos prejudiciais ao meio ambiente como matéria-prima para betões mais sustentáveis. Um exemplo promissor é a terra diatomácea residual (TDR), subproduto gerado no processo de filtração de vinhos, cujas propriedades têm demonstrado resultados positivos na resistência mecânica de argamassas, betões e outros materiais.
Este estudo teve como objetivo avaliar o comportamento do betão com TDR quando submetido a diferentes patamares de temperatura (20 °C, 250 °C, 350 °C, 500 °C) por meio da exposição a diferentes regimes de arrefecimento (gradual e acelerado) e idade pós-arrefecimento (24 horas e 28 dias). O programa experimental envolveu a produção de provetes cúbicos utilizando: betão de referência (REF), TDR em substituição parcial de 10% cimento (RC) e TDR em substituição parcial de 5% de areia (RA). Estas percentagens foram definidas em estudos prévios como teores ótimos de incorporação da TDR sem alterar as propriedades físicas e mecânicas do betão.
Os resultados indicaram que a incorporação de TDR resultou em resistência estatisticamente igual em comparação ao traço de referência para a temperatura ambiente. Contudo, quando expostos a altas temperaturas as composições com TDR apresentaram maior variabilidade entre a resistência residual dos provetes, indicando maior sensibilidade do material ao aquecimento. Ademais, as composições RC e RA apresentaram redução de massa em comparação com a composição REF, mas não foi identificada relação entre esta variação e a resistência residual.
O arrefecimento em água contribuiu para a recuperação da resistência residual, com recuperação de 148% na composição REF, 139% na RC e 136% na RA após 28 dias de cura pós-aquecimento em câmara úmida em comparação com os resultados em 24h.
Quando expostos a 500 °C, os provetes contendo TDR apresentaram explosive spalling, possivelmente relacionada a granulometria fina do material que preenche os vazios e torna a composição mais densa. Em geral, os resultados sugerem que a TDR é um material promissor para substituição parcial do cimento e, principalmente, da areia. O bom desempenho observado está associado à composição rica em sílica da TDR, que favorece a resistência do betão.
The construction sector, while playing its essential role in the provision of housing and infrastructure, faces the challenge of reducing the environmental impacts resulting from its activities. In this context, research focused on the incorporation of environmentally harmful waste as raw material for more sustainable concrete stands out. A promising example is the residual diatomaceous earth (RDT), a by-product generated in the wine filtration process, whose properties have shown positive results in the mechanical resistance of mortars, concrete and other materials. This study aimed to evaluate the behavior of concrete with TDR when subjected to different temperature levels (20 °C, 250 °C, 350 °C, 500 °C) by exposure to different cooling regimes (gradual and accelerated) and post-cooling age (24 hours and 28 days). The experimental program involved the production of cubic test pieces using: reference concrete (REF), TDR in partial replacement of 10% cement (RC) and TDR in partial replacement of 5% sand (RA). These percentages were defined in previous studies as optimal levels of incorporation of TDR without changing the physical and mechanical properties of concrete. The results indicated that the incorporation of TDR resulted in resistance statistically equal compared to the reference trace for room temperature. However, when exposed to high temperatures the compositions with TDR showed greater variability between the residual strength of the test pieces, indicating greater sensitivity of the material to heating. In addition, the RC and RA compositions showed a reduction of mass compared to the REF composition, but no relationship was identified between this variation and the residual resistance. Water cooling contributed to the recovery of residual resistance, with a recovery of 148% in REF composition, 139% in CR and 136% in AR after 28 days of wet chamber post-heating cure compared to results in 24h. When exposed to 500 °C, the test pieces containing TDR showed explosive spalling, possibly related to fine grain size of the material that fills the voids and makes the composition denser. In general, the results suggest that TDR is a promising material for partial replacement of cement and especially sand. The good performance observed is associated with the silica-rich composition of TDR, which favors the strength of concrete.
The construction sector, while playing its essential role in the provision of housing and infrastructure, faces the challenge of reducing the environmental impacts resulting from its activities. In this context, research focused on the incorporation of environmentally harmful waste as raw material for more sustainable concrete stands out. A promising example is the residual diatomaceous earth (RDT), a by-product generated in the wine filtration process, whose properties have shown positive results in the mechanical resistance of mortars, concrete and other materials. This study aimed to evaluate the behavior of concrete with TDR when subjected to different temperature levels (20 °C, 250 °C, 350 °C, 500 °C) by exposure to different cooling regimes (gradual and accelerated) and post-cooling age (24 hours and 28 days). The experimental program involved the production of cubic test pieces using: reference concrete (REF), TDR in partial replacement of 10% cement (RC) and TDR in partial replacement of 5% sand (RA). These percentages were defined in previous studies as optimal levels of incorporation of TDR without changing the physical and mechanical properties of concrete. The results indicated that the incorporation of TDR resulted in resistance statistically equal compared to the reference trace for room temperature. However, when exposed to high temperatures the compositions with TDR showed greater variability between the residual strength of the test pieces, indicating greater sensitivity of the material to heating. In addition, the RC and RA compositions showed a reduction of mass compared to the REF composition, but no relationship was identified between this variation and the residual resistance. Water cooling contributed to the recovery of residual resistance, with a recovery of 148% in REF composition, 139% in CR and 136% in AR after 28 days of wet chamber post-heating cure compared to results in 24h. When exposed to 500 °C, the test pieces containing TDR showed explosive spalling, possibly related to fine grain size of the material that fills the voids and makes the composition denser. In general, the results suggest that TDR is a promising material for partial replacement of cement and especially sand. The good performance observed is associated with the silica-rich composition of TDR, which favors the strength of concrete.
Description
Mestrado de dupla diplomação com a Universidade Tecnológica Federal do Paraná
Keywords
Altas temperaturas Arrefecimento Betão Terra diatomácea residual Resistência residual