Effect of set retarder on the hydratation mechanism and microestructure of plaster of Paris

The objective of this work was to evaluate the effect of set retarding chemicals on plaster of Paris hydration and microstructure. Contents added were 0,03% citric acid, 0,8% caseyne and 1,5% gelatine. The evolution of the hydration was followed by calorimetry measurement and the microstruture ibser...

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Main Authors:	Hincapie, Angela Maria, Cincotto, Maria Alba
Format:	Online
Language:	por
Published:	ANTAC - Associação Nacional de Tecnologia do Ambiente Construído 2008
Online Access:	https://seer.ufrgs.br/ambienteconstruido/article/view/3350
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id	ojs-article-3350
record_format	ojs
spelling	ojs-article-33502008-05-09T18:20:36Z Effect of set retarder on the hydratation mechanism and microestructure of plaster of Paris Efeito de retardadores de pega no mecanismo de hidratação e na microestrutura do gesso de construção Hincapie, Angela Maria Cincotto, Maria Alba Hidratação; Gesso de construção; Retardadores; Microestrutura The objective of this work was to evaluate the effect of set retarding chemicals on plaster of Paris hydration and microstructure. Contents added were 0,03% citric acid, 0,8% caseyne and 1,5% gelatine. The evolution of the hydration was followed by calorimetry measurement and the microstruture ibserved by scanning electron microscope. The results show that the effect of these retarders can be classified into two groups: 1) the first one, composed of citric acid and borax, affects the induction period, but not the reaction rate; 2) the second one, composed of caseune and gelatine, affects both the induction period and and the rate of hydration. No significant change in the shape of crystals was observed; with borax the crystals have a hexagonal but irregular shape. With the addition of gelatyne, the crystals are thick, rounded and smaller than the crystals formed with no retarder added. O Objetivo do trabalho é avaliar a influência dos retardadores de pega na hidratação e microestrutura do gesso de construção. Para o estudo foram adicionados teores de 0,03% de ácido cítrico, 0,8% de bórax, 8% de caseína e 1,5% de gelatina. A evolução hidratação foi acompanhada por calorimetria e a microestrutura observada em microscópio eletrônico de varredura. Os resultados mostraram que o efeito dos retardadores na reação de hidratação pode ser dividido em dois grupos: 1) um primeiro grupo, composto por ácido cítrico e bórax, os quais afetam o período de indução, porém sem afetar a velocidade de reação; 2) um segundo grupo, composto por caseína e gelatina, as quais afetaram tanto o período de indução, como diminuíram a taxa de reação de hidratação. Foi observado que em presença de ácido cítrico e caseína não ocorre uma mudança significativa dos cristais de gipsita; já com adição de bórax os cristais apresentam-se com forma hexagonal e irregular. Com a adição de gelatina, os cristais que se formam são grossos, arredondados e de menor tamanho que os cristais de gipsita formados quando não é adicionado retardador. ANTAC - Associação Nacional de Tecnologia do Ambiente Construído 2008-04-14 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion application/pdf https://seer.ufrgs.br/ambienteconstruido/article/view/3350 Ambiente Construído; v. 1, n. 2 (1997): Edição Especial O Gesso na Construção; 7-16 Ambiente Construído; v. 1, n. 2 (1997): Edição Especial O Gesso na Construção; 7-16 Ambiente Construído; v. 1, n. 2 (1997): Edição Especial O Gesso na Construção; 7-16 1678-8621 1415-8876 por https://seer.ufrgs.br/ambienteconstruido/article/view/3350/1801 Direitos autorais 2016 Ambiente Construído https://creativecommons.org/licenses/by/4.0
institution	Universidade Federal do Rio Grande do Sul
collection	OJS
language	por
format	Online
author	Hincapie, Angela Maria Cincotto, Maria Alba
spellingShingle	Hincapie, Angela Maria Cincotto, Maria Alba Effect of set retarder on the hydratation mechanism and microestructure of plaster of Paris
author_facet	Hincapie, Angela Maria Cincotto, Maria Alba
author_sort	Hincapie, Angela Maria
title	Effect of set retarder on the hydratation mechanism and microestructure of plaster of Paris
title_short	Effect of set retarder on the hydratation mechanism and microestructure of plaster of Paris
title_full	Effect of set retarder on the hydratation mechanism and microestructure of plaster of Paris
title_fullStr	Effect of set retarder on the hydratation mechanism and microestructure of plaster of Paris
title_full_unstemmed	Effect of set retarder on the hydratation mechanism and microestructure of plaster of Paris
title_sort	effect of set retarder on the hydratation mechanism and microestructure of plaster of paris
description	The objective of this work was to evaluate the effect of set retarding chemicals on plaster of Paris hydration and microstructure. Contents added were 0,03% citric acid, 0,8% caseyne and 1,5% gelatine. The evolution of the hydration was followed by calorimetry measurement and the microstruture ibserved by scanning electron microscope. The results show that the effect of these retarders can be classified into two groups: 1) the first one, composed of citric acid and borax, affects the induction period, but not the reaction rate; 2) the second one, composed of caseune and gelatine, affects both the induction period and and the rate of hydration. No significant change in the shape of crystals was observed; with borax the crystals have a hexagonal but irregular shape. With the addition of gelatyne, the crystals are thick, rounded and smaller than the crystals formed with no retarder added.
publisher	ANTAC - Associação Nacional de Tecnologia do Ambiente Construído
publishDate	2008
url	https://seer.ufrgs.br/ambienteconstruido/article/view/3350
work_keys_str_mv	AT hincapieangelamaria effectofsetretarderonthehydratationmechanismandmicroestructureofplasterofparis AT cincottomariaalba effectofsetretarderonthehydratationmechanismandmicroestructureofplasterofparis AT hincapieangelamaria efeitoderetardadoresdepeganomecanismodehidratacaoenamicroestruturadogessodeconstrucao AT cincottomariaalba efeitoderetardadoresdepeganomecanismodehidratacaoenamicroestruturadogessodeconstrucao
_version_	1709370563186655232

Effect of set retarder on the hydratation mechanism and microestructure of plaster of Paris

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