Cinza de biomassa rica em calcário como material carbonático em sistemas cimentícios de base Portland

Abstract

Resumo O uso de materiais alternativos, em substituição ao clínquer, tem sido amplamente estudado, a fim de reduzir custos e minimizar os danos ambientais causados pela produção do cimento Portland. Investigou-se a influência do uso da cinza de algaroba (Prosopis juliflora), material rico em carbonato de cálcio, nos mecanismos de hidratação e formação das principais fases hidratadas do cimento Portland. As características físicas e químicas das matérias-primas foram avaliadas. Composições com 5%, 10% e 15% de cinza de algaroba foram analisadas e comparadas com o cimento Portland comercial com fíler calcário (6-10%), CPII-F. A cinza de algaroba é um potencial fíler alternativo para aplicação em sistemas cimentícios de base Portland, atuando de forma semelhante ao fíler calcário em termos de nucleação da fase C-S-H, estabilização da etringita e tendência à formação de carboaluminatos.

Self-compacting concrete using calcium-rich ashes as alternative fillers and heated dry materials to simulate hot weather mixing

“…The size of Algaroba wood ash grains that pass through sieve no. 200 is between 2.46 μm and 43.91 μm (NASCIMENTO et al, 2019;MELO et al, 2018), which is within the grain size required to use as a filler in SCC systems. Thus, owing to the similarity of this type of ash with the natural limestone filler regarding its chemical composition and possible treatments in the physical aspect, it is observed that SCC can incorporate calcium-rich ashes as an alternative filler to ensure its fluidity.…”

“…Likewise, no losses were observed in the SCC compression strengths for TFC (100% of limestone filler), and TFCFA (50% of limestone filler + 50% of calcium-rich ash filler) and their respective corrections when exposed to heat during the mixing process. Nascimento et al (2019) also reported the precipitation of hemicarboaluminate and monocarboaluminate phases in calcium-rich systems using Albaroba ashes.…”

“…As the limestone filler is a non-renewable source, the possibility of using calcium-rich ash is evaluated because it is composed mainly of calcium carbonate (around 70% -80% CaCO3) without expansive oxides (LELOUP, 2013;NASCIMENTO, 2014;NASCIMENTO et al, 2019;MOURA et al, 2021;MELO et al, 2018). The size of Algaroba wood ash grains that pass through sieve no.…”

Effects of storage temperature and time on false setting behavior of CPI-S Portland cement

“…The calcium and silicon oxides were the major constituents in the studied samples and together were responsible for the hydration reactions of silicates, corresponding to more than 60% of volume in the cement reactions [6]. The variation of the calcium and silicon elements in the cement directly interferes in the C 3 S and C 2 S anhydrous phases, in which a higher concentration of calcium leads to a preponderant production of alite, and is the main element responsible for the hydrated C-S-H and Ca(OH) 2 phases [30,31]. The aluminum and iron oxides are no less important, being responsible for aluminate reactions and corresponding to 20% of the volume of the reactions which occur in the cement.…”

Caracterização microestrutural e mineralógica da cinza de biomassa decorrente da queima em caldeiras de lavanderia de jeans

“…Segundo Nascimento et al, (2019), o uso do filler calcário alternativo como substituto parcial do clínquer, na produção do cimento, reduz o consumo energético e a emissão de dióxido de carbono (CO2), além de reduzir a exploração de calcário e argila, que são as matérias-primas do clínquer.…”