Estudo da argamassa de geopolímero para fabricação de placas cimentícias: características físicas, mecânicas, químicas e desempenho ambiental
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Data
2022-12-09
Autores
Soares, Ivana Helena de La-Rocque
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Universidade Estadual Paulista (Unesp)
Resumo
Diante do avanço tecnológico, em um mundo globalizado, quando o desempenho ambiental está em linha de colisão com as necessidades humanas, principalmente no que diz respeito ao destino dos resíduos, são necessárias pesquisas que busquemformas de atender a futura demanda por materiais com redução do impacto ambiental. Deste modo a substituição de materiais convencionais por alternativos que possam mitigar o impacto ambiental, é uma solução promissora. Dentre essas, a substituição de areia por resíduo plástico, em argamassas, apresenta-se como grande potencial. Neste contexto, o presente trabalho teve como objetivo investigar uma nova alternativa de produção de argamassa geopolimérica, utilizando caulim do estado do Amazonas e substituindo areia por resíduo plástico de polietileno de baixa densidade (PEBD), produzindo-se um novo material para a construção civil. O caulim foi beneficiado e caracterizado termicamente por meio de termogravimetria na temperatura de 6500C por 1 h e mostrou ser eficiente para a produção da metacaulinita. Assim, após a calcinação do caulim, a metacaulinita foi caracterizada por MEV, FRX, DRX com refinamento por Rietveld, análise de massa específica e granulometria. As demais matérias-primas, tal como a areia e o resíduo plástico, também foram caracterizadas por MEV, análise de massa específica e granulometria. As argamassas foram produzidas em dois grupos identificadas conforme o tipo de ativador alcalino e o teor de substituição de areia por resíduo plástico. Os dois grupos foram: GP-S geopolímero com ativador simples de hidróxido de sódio NaOH e o outro foi GP-C geopolímero com ativador composto de NaOH e silicato de sódio Na2SiO3. Os grupos de argamassa foram caracterizados de acordo com a sua resistência à compressão, porosidade, absorção de água, fases mineralógicas por DRX, morfologia por MEV e mecanismo de eflorescência. Os resultados mostraram que o grupo das argamassas GP-C a GP50-C teve o melhor desempenho de resistência à compressão com 22,69 MPa aos 28 dias, além de não terem formado eflorescência. A argamassa com melhor desempenho mecânico foi utilizada na produção da placa cimentícia que foi caracterizada quanto à resistência à tração na flexão. Além disso, a placa cimentícia foi estudada quanto ao ciclo de vida pelos métodos ReCipe 2016 Midpoint/Endepoint e EN 15804. A resistência à tração na placa GP50-C foi de 65 MPa, superando a resistência de placas cimentícias produzidas com fibras vegetais. Na avaliação do ciclo da vida, o resíduo plástico mitigou o impacto na categoria do uso da terra em 10%. O uso da metacaulinita em relação ao cimento, se mostrou um material sustentável em cinco categorias. A produção de placa cimentícia de geopolímero de metacaulinita, com substituição da areia por resíduo plástico, contribui como uma alternativa sustentável que pode ser uma opção para mitigar os problemas ambientais ocasionados pelo descarte indevido dos materiais plásticos.
Given the technological advances, in a globalized world in which environmental performance is in line with human needs, especially with regard to the destination of waste, research is needed to find ways to meet the future demand for materials with reduced environmental impact. Thus, the replacement of conventional materials with alternatives that can mitigate environmental impacts is a promising solution. Among these, the replacement of sand by plastic waste in mortars presents itself as having great potential. In this context, the present work aimed to investigate a new alternative for the production of geopolymeric mortar, using kaolin from the state of Amazonas and replacing the sand with low density polyethylene (LDPE) plastic waste, in order to produce a new material for civil construction. The kaolin was processed and thermally characterized using thermogravimetry at a temperature of 650 oC for 1 h and was shown to be efficient for the production of metakaolinite. Thus, after calcination of the kaolin, the metakaokaolinite was characterized using SEM, XRF, XRD with refinement using the Rietveld method, specific mass analysis and granulometry. The other raw materials, such as sand and plastic waste, were also characterized using SEM, specific mass analysis and granulometry. The mortars were produced in two groups, which were identified according to the type of alkaline activator and the level of replacement of sand by plastic waste. The two groups were: the GP-S geopolymer with a simple sodium hydroxide (NaOH) activator and the other was the GP-C geopolymer with an activator composed of NaOH and sodium silicate (Na2SiO3). The mortar groups were characterized according to their compressive strength, porosity, water absorption, mineralogical phases using XRD, morphology using SEM and their efflorescence mechanism. The results showed that the group of GP-C to GP50-C mortars had the best compressive strength performance with 22.69 MPa at 28 days, in addition to not forming efflorescence. The mortar with the best mechanical performance was used in the production of cement plates, which were characterized in terms of tensile strength in bending. In addition, the cement plate was studied regarding its life cycle using the ReCipe 2016 Midpoint/Endpoint and EN 15804 methods. The tensile strength of the GP50-C plate was 65 MPa, surpassing the strength of cement plates produced with vegetable fibers. In the life cycle assessment, plastic waste mitigated the impact on the land use category by 10%. The use of metakaolinite in relation to cement was shown to be a sustainable material in five categories. The production of metakaolinite geopolymeric cement plates, with replacement of sand with plastic waste, is a sustainable alternative that can be an option to mitigate environmental problems caused by improper disposal of plastic materials.
Given the technological advances, in a globalized world in which environmental performance is in line with human needs, especially with regard to the destination of waste, research is needed to find ways to meet the future demand for materials with reduced environmental impact. Thus, the replacement of conventional materials with alternatives that can mitigate environmental impacts is a promising solution. Among these, the replacement of sand by plastic waste in mortars presents itself as having great potential. In this context, the present work aimed to investigate a new alternative for the production of geopolymeric mortar, using kaolin from the state of Amazonas and replacing the sand with low density polyethylene (LDPE) plastic waste, in order to produce a new material for civil construction. The kaolin was processed and thermally characterized using thermogravimetry at a temperature of 650 oC for 1 h and was shown to be efficient for the production of metakaolinite. Thus, after calcination of the kaolin, the metakaokaolinite was characterized using SEM, XRF, XRD with refinement using the Rietveld method, specific mass analysis and granulometry. The other raw materials, such as sand and plastic waste, were also characterized using SEM, specific mass analysis and granulometry. The mortars were produced in two groups, which were identified according to the type of alkaline activator and the level of replacement of sand by plastic waste. The two groups were: the GP-S geopolymer with a simple sodium hydroxide (NaOH) activator and the other was the GP-C geopolymer with an activator composed of NaOH and sodium silicate (Na2SiO3). The mortar groups were characterized according to their compressive strength, porosity, water absorption, mineralogical phases using XRD, morphology using SEM and their efflorescence mechanism. The results showed that the group of GP-C to GP50-C mortars had the best compressive strength performance with 22.69 MPa at 28 days, in addition to not forming efflorescence. The mortar with the best mechanical performance was used in the production of cement plates, which were characterized in terms of tensile strength in bending. In addition, the cement plate was studied regarding its life cycle using the ReCipe 2016 Midpoint/Endpoint and EN 15804 methods. The tensile strength of the GP50-C plate was 65 MPa, surpassing the strength of cement plates produced with vegetable fibers. In the life cycle assessment, plastic waste mitigated the impact on the land use category by 10%. The use of metakaolinite in relation to cement was shown to be a sustainable material in five categories. The production of metakaolinite geopolymeric cement plates, with replacement of sand with plastic waste, is a sustainable alternative that can be an option to mitigate environmental problems caused by improper disposal of plastic materials.
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Palavras-chave
Argamassa de geopolímero, Metacaulinita, Eflorescência, Placa cimentícia, Desempenho ambiental, Geopolymeric mortar, Metakaolinite, Efflorescence, Cement plate, Environmental performace