External ammonium sulfate attack in concrete: Analysis of the current methodology

Martins, Monalisa C.; Langaro, Eloise Aparecida; Macioski, Gustavo; Medeiros, Marcelo Henrique Farias de

doi:10.1016/j.conbuildmat.2021.122252

Cited by 22 publications

(12 citation statements)

References 34 publications

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“…Ag/AgCl ISEs have been shown to provide high selectivity for chlorides allowing for their application to measurements on concrete despite the high content of other ions that might interfere with the measurement. , In our study, the effect of potentially interfering ions resulting from the environmental exposition of concrete to urban areas was further evaluated in the case of our experimental device. Carbonates/bicarbonates and sulfates were selected as species that likely adsorb on concrete constructions as a consequence of the carbonation phenomenon and of corrosive agents from atmospheric particulate in polluted urban areas. − As shown in Figure C, the presence of 10 –1 M of these agents, added to the KCl working solution, did not significantly affect the potentiometric signal, confirming the reliability of the device’s analytical response.…”

Section: Resultsmentioning

confidence: 75%

Vertical-Flow Paper Sensor for On-Site and Prompt Evaluation of Chloride Contamination in Concrete Structures

et al. 2021

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Corrosion occurring in reinforced concrete has turned into a primary concern of the current century, concrete being the most ubiquitous and predominant material used in the construction industry. Among the many interrelated processes that trigger corrosion of metallic reinforcements, the penetration of chloride ions into the concrete matrix is the most insidious threat. Herein, we developed the first electrochemical device entirely made of paper that allows for the direct, prompt, and noninvasive evaluation of free chloride ion contamination in concrete-based constructions. Our device is based on a three-layer wax-modified filter paper, consisting of two Ag/AgCl screen-printed electrodes that are interfaced by a junction pad in a sandwich-like configuration. Filter paper allows for generating a vertical-flow potentiometric device capable of measuring the electrochemical potential between two solutions containing different concentrations of chloride ions, which are separately drop-cast on the top and bottom layers. After demonstrating the analytical performance of the device, the same principle was applied to the evaluation of the chloride contents in different concrete samples, exploiting paper as a suitable interfacing material for potentiometric measurements on the cement solid surface. Laboratory-prepared concrete samples with known chloride contents were first assessed, and then, the paper-based verticalflow device was applied to real concrete structures at the Giacomo ManzùMuseum (Ardea, Italy) for the evaluation of chloride contamination caused by the proximity to the seaside. The capability of our device to provide timely warning of the risk conditions of concrete-based artifacts was demonstrated.

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Section: Resultsmentioning

confidence: 75%

Vertical-Flow Paper Sensor for On-Site and Prompt Evaluation of Chloride Contamination in Concrete Structures

et al. 2021

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“…Another important external sulfate attack studied using the ammonium sulfate solution ( Girardi and Maggio, 2011 ; Martins et al, 2021 ) presents a deterioration of concrete due to the secondary gypsum and secondary ettringite formation ( Brown, 2002 ), similar to Na 2 SO 4 and MgSO 4 mechanism attacks. Moreover, the C-S-H degradation was detected in this chemical aggression type ( Marchand et al, 2001 ; Martins et al, 2021 ), which may eventually convert into amorphous hydrated silica (R°6). This external attack caused cracks and decomposition of concrete mainly in the interfacial zone ( Girardi and Maggio, 2011 ).…”

Section: Bibliographic Reviewmentioning

confidence: 99%

Natural Resources Exploitation in Sulfate-Resisting Portland Cement Manufacturing: Towards Quality Improvement and Reduction of Environmental Impact

Labidi

Megriche

2022

Front. Chem.

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Sulfate-resisting (SR) Portland cement is commonly used in building works to improve concrete’s durability against external sulfate attack. This attack is considered a very serious chemical aggression that causes damage and cracking of concrete structures. These special cements have a very particular mineralogical composition, C3A ≤ 3% and (2C3A + C4AF) ≤ 20%, which makes the cementitious matrix resistant to sulfate attack. This kind of product is very difficult to manufacture since low alumina (C3A) necessitates the use of a high kiln temperature in order to keep a sufficient liquid phase necessary to maintain the stability of the cement manufacturing process. In this context, this study aims to optimize SR Portland cement raw meals using natural materials collected from different regions in Tunisia, mainly ordinary limestone, siliceous limestone, black marl, grey marl, iron ore, and natural fluorapatite. The collected specimens were characterized by an X-ray fluorescence spectrometer in order to determine its elemental chemical composition. The optimization of the SR Portland cement raw meal combinations was done by means of a calculation tool based on the chemical composition of each used raw material and the variation of burning modules (LSF, SIM, and ALM). It has been found that natural fluorapatite integration (0%–15%) in raw mix preparation leads to the raw meals required for the SR Portland cement standard (C3A ≤ 3% et 2 C3A + C4AF ≤ 20%). Moreover, it was shown that the estimated SR raw meals ensure the cement manufacturing process stability (acceptable burning modules “LSF = 100; SIM = 3; ALM = 0.91 and sufficient liquid phase) and decrease the CO2 emissions in cement production.

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“…Os dados de difração de todas as amostras da tese são coletados em um difratômetro, operando em modo de transmissão, usando a radiação CuKα1 (λ = 1,54056 Å), na faixa de 10 a 70 °, com tamanhos de grau de 0,015 ° e um tempo de contagem de 100s a cada 1,05 °. Para a análise de DRX, após a idade de 28 dias, as amostras foram transformadas em fragmentos e imersos em álcool isopropílico por um período de 24h e, em seguida, secas em estufa a 40 ºC por mais 24h, período de secagem, a fim de interromper a hidratação das pastas [38,39].…”

Section: Ensaiosunclassified

“…Os difratogramas das pastas cimentícias e cimentícias-pozolânicas com adição de FC e do sistema FC/MCC, aos 28 dias de cura, com picos de intensidade normalizados, são apresentados nas Figuras 9 e 10. A partir das comparações dos difratogramas produzidos pela presente análise com difratogramas encontrados na literatura [27,39,[55][56][57] foi possível identificar as fases cristalinas a partir da hidratação da amostra de referência (sem celuloses FC e MCC) e dos diferentes compósitos produzidos. Os padrões de difração de raios-X das amostras com e sem adição das celuloses FC/MCC mostraram os produtos de hidratação esperados, incluindo a presença de portlandita (P) (2θ = 18,26º; 34,38º; 48,94º) calcita (C) (2θ = 29,65º) e silicato de cálcio hidratado (CS) (2θ = 32,54º).…”

Section: Efeito Da Hidratação Por Difração De Raios-x Das Pastas Cime...unclassified

Efeito do reforço multi-escala fibra de celulose-microcelulose cristalina na fase de hidratação de pastas de cimento Portland

2022

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RESUMO A utilização de fibras celulósicas em matrizes cimentícias pode apresentar um efeito inibitório causando incompatibilidade química e inviabilizando o processo de produção de materiais de construção civil reforçados com fibras de celulose. Já as microceluloses geralmente aceleram a produção de gel de hidrato de silicato de cálcio (CSH) acelerando o grau de hidratação do cimento. Assim, o presente trabalho tem por objetivo o entendimento das interações combinadas entre microcelulose cristalina e fibra de celulose (MCC e FC) no processo de hidratação das pastas cimentícias. Os resultados obtidos no ensaio de inibição das pastas apontaram uma boa compatibilidade das fibras celulósicas e do sistema FC/MCC com as pastas cimentícias. Já para pastas cimentícias com substituição de cinza volante, o sistema FC/0,6%MCC apresentou moderada inibição apresentando diferença estatística significativa em relação aos demais tratamentos. Através do ensaio de difração de raios—X foi possível concluir que tanto as fibras celulósicas quanto o sistema FC/MCC não influenciaram na mineralogia dos compósitos, onde os padrões de difração mostraram os produtos de hidratação típicos dos aglomerantes minerais. Na análise de DRX foi possível identificar a redução dos picos de magnitude da Portlandita, com a incorporação de celulose MCC nas pastas cimentícias, o que indica menor disponibilidade de produtos C-S-H, podendo correlacionar com o retardo na hidratação das pastas cimentícias contendo celuloses FC/MCC.

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External ammonium sulfate attack in concrete: Analysis of the current methodology

Cited by 22 publications

References 34 publications

Vertical-Flow Paper Sensor for On-Site and Prompt Evaluation of Chloride Contamination in Concrete Structures

Vertical-Flow Paper Sensor for On-Site and Prompt Evaluation of Chloride Contamination in Concrete Structures

Natural Resources Exploitation in Sulfate-Resisting Portland Cement Manufacturing: Towards Quality Improvement and Reduction of Environmental Impact

Efeito do reforço multi-escala fibra de celulose-microcelulose cristalina na fase de hidratação de pastas de cimento Portland

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