adotadas [19]. Diferentes autores têm estudado a desidratação e reidratação da PCH em diferentes condições [22]. Peng e Huang [23] prepararam amostras de PCH e submeteram a 90 dias de cura em água; em seguida estas foram tratadas a diferentes temperaturas durante 8 h. O estudo do difratograma da amostra obtida a 800 °C revelou com clareza que o C-S-H se decompõe em beta silicato dicálcico (β-C 2 S) nesta Mecânica, Pr. Frei Orlando 170, MG, einstein@ufsj.edu.br, adrianogalvao26@yahoo.com.br, strecker@ufsj.edu.br Resumo Devido aos impactos ambientais gerados pela construção civil, muitos pesquisadores têm estudado os resíduos de construção e demolição. É possível encontrar na literatura científica trabalhos focados na pasta de cimento endurecido. Neste estudo, pasta de cimento Portland hidratada (PCH) preparada a partir de cimento Portland CP V-ARI (CP-V) foi desidratada via tratamento térmico a 700 °C (700-PCD) e a 900 °C (900-PCD), sendo em seguida reidratada. A estrutura e microestrutura durante hidratação, desidratação e reidratação foram investigadas. Para a caracterização das mudanças morfológicas, difração de raios X, espectroscopia no infravermelho com transformada de Fourier e microscopia eletrônica de varredura foram utilizadas. A análise termogravimétrica foi utilizada para estudar as etapas de desidratação da pasta de cimento hidratada original. O estudo de desidratação da PCH mostrou que a 700 e 900 °C os novos nesossilicatos e CaO estão claramente presentes nas amostras. Durante a reidratação das amostras de 700-PCD e o 900-PCD, ocorreram reidratação parcial e carbonatação. Corpos de prova a partir de CP-V e 0%, 2%, 10%, 40% e 60% de pó de cimento desidratado (PCD) foram preparados. Corpos de prova preparados com até 40% de PCD apresentaram propriedades semelhantes, quando comparado com corpos de prova de pasta de cimento puro preparados com CP-V, enquanto adições de 60% de PCD resultaram em um decréscimo da resistência à compressão. Palavras-chave: pasta de cimento, pasta de cimento desidratado, reidratação, resistência à compressão, porosidade. 2%,10%, 40% and 60% of dehydrated cement powder (PCD) were prepared. Specimens prepared with up to 40% of PCD showed similar properties when compared to the pure cement paste prepared from CP-V, while additions of 60% PCD resulted in a decrease of the compressive strength. Abstract Because of the environmental impacts generated by civil construction, many researchers have studied the wastes of construction and demolition. It is possible to find in the scientific literature works focused on hardened cement paste. In this study, hydrated Portland cement paste (PCH) prepared from Portland cement CP V-ARI (CP-V) was dehydrated through heat treatments at
The consumption of polymeric materials and their waste increases considerably throughout the world, leading to a constant concern with alternative recycling routes. Polypropylene (PP) waste is produced in large volumes, but it is not recycled in an expressive way. A significant amount of research has been conducted to recycle discarded material into cement-based composites, combining environmental, economic, and technological issues. Nondestructive tests, such as ultra-pulse velocity (UPV), can be used to characterize and estimate the physical and mechanical properties of cement-based materials. This work investigates the effect of the partial replacement of natural aggregates (NA) with recycled PP aggregates on the pulse velocity and physic-mechanical properties of impact-compacted mortars and their correlations. Coarse particles of PP (at 4–10 US-Tyler and 10–20 US-Tyler) provided better mechanical behavior to composites than fine particles (20–50 US-Tyler), the latter being responsible for a rise in porosity. UPV can be used to predict the physical and mechanical properties of mortars containing PP aggregates.
The consumption of polymeric materials and their waste increases considerably throughout the world, leading to a constant concern with alternative recycling routes. Polypropylene (PP) is one of the most produced, but it is not recycled in an expressive way. A significant amount of research has been conducted to reuse discarded material into new composites, especially the cementitious ones, combining environmental, economic and technological issues. Nondestructive tests, such as ultra-pulse velocity, can be used to characterize and estimate the physical and mechanical properties of cement-based materials. This work investigates the effect of partial replacement of natural aggregates (NA) by recycled PP aggregates (PP-RPA) on pulse velocity and physical-mechanical properties of mortars and their correlations. Coarse particles of PP (at 4-10 US-Tyler and 10-20 US-Tyler) provided better mechanical behaviour to composites made with fine particles (20-50 US Tyler), the latter being largely affected by the presence of pores. Ultra-pulse velocity can be used to predict the physical and mechanical properties of mortars containing PP aggregates.
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