Comparativo entre o teste de Vicat e a calorimetria semi-adiabática para determinação do tempo de início e fim de pega em cimentos Portland

Viecili, Maycon Jonas Consalter; Hastenpflug, Daniel; Girardi, Ricardo

doi:10.1590/s1517-707620180003.0506

Cited by 4 publications

(5 citation statements)

References 1 publication

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“…The greatest differences between the three methods evaluated were obtained for the final setting times, as shown in Figure 11. These differences are due to the fact that the tangent method consider the end of the setting process only when the temperature reaches the maximum peak after the period of induction [27], [29], [49], while in the other methods the end is considered before, being located close to the half of the period of acceleration [26], [50], [51]. In all of the correlations for final setting times, coefficients (r) very close to 1.0 were obtained, demonstrating and excellent correlation between the different methods.…”

Section: Comparison Between the Methods Of Determination Of The Settimentioning

confidence: 99%

“…The thermocouple wire was connected to the data collector ( Figure 3f). Based on the data obtained, three distinct methods were used for the analysis and determination of the initial and final setting times: the tangent method [46], direct fraction method [26], [47] and the derivatives method [48]. In each of the methods the times considered for each mixture was the arithmetic mean between the three samples tested.…”

Section: Mortarmentioning

confidence: 99%

“…The points of intersection between the traced lines correspond to the initial and final setting times. Through the direct fraction method [26], [47] the initial and final setting times are determined by percentages of the total increase of the temperature. This way, in controlled environment conditions, the initial setting time is equivalent to 21% of the difference between the temperature of the beginning of the induction and superior peak of the temperature reached, while the final time is equivalent to 42%, as shown in Figure 5.…”

Section: Mortarmentioning

confidence: 99%

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Influence of cement type, air-entrained admixture and hydration stabilizing admixture on mortars’ setting time

Antoniazzi

Mohamad

Casali

2021

Rev. IBRACON Estrut. Mater.

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Ready mix mortar is a ready to use mixture that uses hydration stabilizing (HSA) and air-entrained (AEA) admixtures in its composition, which modify its properties, especially the setting times. HSA extends the setting time of mortars for a long period, while AEA promotes a greater workability to the mixture. The study determined the temperature of the mortars with the evaluation of the setting times obtained by a semi-adiabatic calorimeter. Two types of cement (CPII-F-40 e CPII-Z-32) and varied contents of HSA (0.0%, 0.6% e 0.9%) and AEA (0.0%, 0.2% e 0.4%) were used. The results showed that the use of HSA decreased the amplitude of the temperature peaks and increased the setting times with cement CPII-Z-32 in relation to cement CPII-F-40. The setting time of the mortars was influenced by the type of cement used and by the contents of the admixtures.

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Section: Comparison Between the Methods Of Determination Of The Settimentioning

confidence: 99%

Section: Mortarmentioning

confidence: 99%

Section: Mortarmentioning

confidence: 99%

See 1 more Smart Citation

Influence of cement type, air-entrained admixture and hydration stabilizing admixture on mortars’ setting time

Antoniazzi

Mohamad

Casali

2021

Rev. IBRACON Estrut. Mater.

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“…O calor de hidratação é uma propriedade importante de ser avaliada, pois influencia diretamente nos aspectos de trabalhabilidade e fluidez das pastas de cimento. É possível avaliar a reatividade dos cimentos Portland a partir das informações da taxa de calor [16]. A taxa de liberação de calor de hidratação, que ocorre após a mistura de uma pasta cimentícia, caracteriza-se por fases distintas.…”

Section: Introductionunclassified

Estudo experimental da compatibilidade entre aditivos químicos e cimento Portland em misturas cimentícias através de calorimetria

Nunes

Polesello

2022

Matéria (Rio J.)

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RESUMO Os aditivos químicos, cada vez mais utilizados na construção civil, vêm desempenhando importante papel na tecnologia de materiais cimentícios por modificarem alguns comportamentos de misturas cimentícias, como a trabalhabilidade e retardo ou aceleração de pega. A grande variedade de aditivos disponível necessita o conhecimento de sua compatibilidade quando utilizados com diferentes composições cimentícias, considerando o tipo de aditivo, teor de dosagem e cimento utilizado na mistura. Para tal, o presente estudo visa analisar a compatibilidade da interação entre cimentos e aditivos, através de curvas calorimétricas geradas a partir de um calorímetro semi-adiabático. A análise foi realizada pela produção de pastas resultantes da composição de misturas entre dois tipos de cimento Portland (CPIV e CPV) e cinco aditivos redutores de água, sendo quatro classificados como plastificantes e um como superplastificante, provenientes de fabricantes distintos, e água. As misturas têm relação água/cimento (a/c) fixada em 0,40 e diferentes teores de dosagens dos aditivos: 0,0%, 0,4%, 0,6%, 0,8% e 1,0%. Os resultados mostraram que a presença de aditivo nas pastas cimentícias tem influência no calor de hidratação gerado e nos tempos de início e fim de pega das pastas. A temperatura máxima diminui e ocorre um retardo considerável no início de pega com a incorporação de maiores quantidades de aditivo plastificante nas pastas estudadas, enquanto que para as pastas produzidas com aditivo superplastificante esse retardo expressivo não foi registrado.

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“…Schematic illustration of length change and heat flow as a function of setting time of a cementitious material having shrinkage compensation by ettringite formation (adapted from[24,86]). …”

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confidence: 99%

Ternary system Portland cement-calcium aluminate cement-calcium sulfate applied to self-leveling mortar: a literature review

2021

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The modernization of building systems is increasingly demanding products that improve efficiency during their processing. The development of self-leveling mortars for the regularization of flooring is a consequence of this evolution. The high contents of binder and water to obtain self-flowing property, plus the application of thin layers over large areas, make this type of mortar susceptible to high shrinkage levels. Thus, the ternary system Portland cement-calcium aluminate cement-calcium sulfate (OPC-CAC-CaSO 4) is a viable solution for shrinkage compensation. The expansion mechanism based on ettringite formation aims to prevent the mortar from cracking. Considering its complexity and that international literature is still limited (while Brazilian is null), this article presents a literature review that covers diverse aspects related to the application of the system OPC-CAC-CaSO 4. The influence of raw materials and mix proportions on rheological behavior, reaction kinetics, development of strength, and length change are discussed.

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Comparativo entre o teste de Vicat e a calorimetria semi-adiabática para determinação do tempo de início e fim de pega em cimentos Portland

Cited by 4 publications

References 1 publication

Influence of cement type, air-entrained admixture and hydration stabilizing admixture on mortars’ setting time

Influence of cement type, air-entrained admixture and hydration stabilizing admixture on mortars’ setting time

Estudo experimental da compatibilidade entre aditivos químicos e cimento Portland em misturas cimentícias através de calorimetria

Ternary system Portland cement-calcium aluminate cement-calcium sulfate applied to self-leveling mortar: a literature review

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