Alkaline activation of high-calcium ash and iron ore tailings and their recycling potential in building materials

Abstract

lkali-activated materials are agglomerates obtained from the alkaline activation of aluminum-and silicone-rich precursors. The most popular precursors for this type of activation are low-calcium fly ashes, blast furnace slag, and metakaolin. However, both high-calcium ashes (HCAs) and iron ore tailings (IOTs) are interesting wastes that can be investigated as precursors because of their available volume and environmental impact during their final deposition. Therefore, by performing tests of compressive strength, FTIR spectrometry and scanning electron microscopy, we sought to identify the products formed during HCA and IOT activation without thermal treatment. Nine mortar formulations with different HCA and IOT proportions were developed using sodium hydroxide and sodium silicate as activators. Thus, using FTIR spectrometry, we observed the reaction between the industrial wastes. Additionally, the compressive strength result suggested that the material could be used as compressed blocks in masonry walls for the development of more environmentally friendly building materials, which would mitigate the impact of waste disposal and convert industrial solid waste into value-added products.

Estudo das propriedades reológicas e microestruturais de ligante geopolimérico à base de cinza volante

“…Entender as características microestruturais dos geopolímeros também é importante, uma vez que a composição física e morfológica dos aluminossilicatos (tamanho, forma e a distribuição granulométrica das partículas) é um dos fatores mais importantes para ativação alcalina (BEZERRA et al, 2019). Dessa forma, estudos são necessários para destacar a importância das propriedades e das dosagens de precursor e de ativador sobre a reologia dos geopolímeros, e para relacionar essas propriedades no estado fresco com a resistência mecânica no estado endurecido.…”

Desenvolvimento de argamassa álcali-ativada baseada em cinzas de caldeira de dendê e queima de madeira

“…Nessa perspectiva, tem-se buscado, entre os resíduos de outras indústrias, potenciais fontes de alumínio, cálcio e silício que possam contribuir para a produção de AAA, sendo encontrados resultados positivos com o uso de escórias de alto forno, cinza volante, rejeitos de mineração e cinzas como as de casca de arroz e bagaço de cana (BEZERRA et al, 2019;DEMBOVSKA et al, 2017;SULTHAN, 2019).…”

Portlandite consumption by red ceramic waste due to alkali activation reaction

“…However, part of the studies in the area of alkali-activated binders and geopolymers do not evaluate how the availability of silicon and calcium influences the reaction, even if these elements, together with aluminum, are the main components in the reaction products that generate mechanical resistance in the compositions. The researchers, mostly, use alkaline bases that are more electropositive, facilitating the integration into the newly formed structure, such as sodium or potassium silicate (BEZERRA et al, 2019;DUXSON et al, 2007;LI;SUN;LI, 2010;PALOMO;GRUTZECK;BLANCO, 1999;TORGAL;JALALI, 2007). However, due to the high cost of these bases, its use is not feasible for incorporation in residues as the ceramic material for the production of a binder by alkali-activation in civil construction on a large scale.…”