Influência dos parâmetros de forma do agregado na formulação de argamassas de projeção
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Data
2018-12-12
Autores
Mello, Cesar Winter
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Resumo
Esse trabalho busca enfatizar a influência dos parâmetros de forma de areias na formulação de argamassas de projeção. O objetivo principal deste trabalho é o de determinar parâmetros de projetabilidade através da análise do fator forma do agregado miúdo e do comportamento reológico para a formulação de argamassas de revestimentos . O programa experimental contou com a seleção de três tipos de agregados , um quartozo de rio (APR), e duas de britagem de origem basáltica, porém uma
britada pelo sistema vertical shaft impactor (VSI) e outra britada pelo sis tema de britador de impacto (CONV). Foram produzidas cinco composições granulométricas (CG-APR, CG-VSI, CG-CONV, CG-VSI 1 e CG-CONV 1) sendo que as duas últimas corrigidas com a CG-APR, buscando suprir a defasagem de finos das areias britadas. Foram feitas as caracterizações física e parâmetros de forma das areias através de ensaios prescritos pelas normas brasileiras e análise morfológica e aquisição de imagens pela lupa estereoscópica e posterior tratamento das mesmas utilizando o software ImageJ. Produziram - se 15
dosagens de argamassas de projeção utilizando as composições em três diferentes proporcionamentos, quais sejam: 1:1:4 (T1), 1:1:6 (T2) e 1:1:8 (T3) (cimento:cal:areia, materiais secos em massa). As argamassas foram caracterizadas nos estados fresco e endurecido e submetidas a ensaios reológicos através das técnicas de reometria rotacional e de squeeze -flow além de teste de projeção. Após transcorrido pelo menos 28 dias de cura realizou -se a caracterização dos revestimentos através dos
ensaios de resistência de aderência à tração e permeabilidade pelo método do cachimbo. Os resultados mostraram que as areias apresentaram diferenças significativas quanto aos parâmetros de forma (forma, arredondamento e esfericidade) sendo que as composições CG-APR, CG-VSI 1, CG- VSI e CG-CONV 1 foram consideradas como bem arredondadas e CG-CONV como arredondada. Considerando os ensaios de squeeze-flow verificou- se influência da composição granulométrica nas argamassas, visto que àquelas produzidas com as composições mais grossas mostraram-se mais rígidas, produzindo menores
deformações e com elevadas cargas de aplicação. Pode-se inferir que o fator forma gera influência na resistência ao fluxo que contêm grãos com formas irregulares e com superfícies rugosas. Já os resultados de reometria rotacional mostraram que o agregado fino influência nos parâmetros reológicos analisados. Pôde- se perceber que os principais fatores que influenciaram significativamente no comportamento reológico das argamassas de projeção foram os parâmetros de forma e granulometria dos agregados, ar incorporado e densidade de massa. Os ensaios de resistência de aderência à tração e permeabilidade pelo método do cachimbo realizados nos revestimentos produzidos mostraram influência significativa dos parâmetros de forma, granulometria e dosagem das argamassas analisadas. Deste modo pode- se traçar parâmetros reológicos limites os quais são: fator forma utilizável (rugosos e polidos a polidos, arredondados e de baixa esfericidade), composição granulométrica utilizável (agregados com maior porcentagem de finos passantes na peneira #0,6mm) e viscosidade aparente entre 14 a 28 Pa.s para grãos polidos e 16 a 48 Pa.s. para grãos rugosos e polidos.
This study emphasize the influence of aggregate shape parameters on the mix design of sprayed mortars. The main objective of this work is to determine the parameters of projectability through the analysis of the form factor of the sands and rheology for the mix design of mortars of coatings. The experimental program consisted of the selection of three types of sands, one river quartz (APR), and two crusher of basaltic origin, one crushed by the vertical shaft impactor system (VSI) and the other crushed by the impact crusher system CONV). Fi ve compositions were produced, CG-APR, CG-VSI, CG-CON V, CG-VSI 1 and CG-CONV 1, the last two of which were corrected with CG-APR, aiming to overcome the demarcation of fines from the crushed sands. The physical characterization and shape parameters of the sands were performed through tests prescribed by the Brazilian standards and morphological analysis and image acquisition by the stereoscopic loupe and subsequent treatment of them using the ImageJ software. 15 means of sprayed mortars were made using the compositions in three different mix design, which are: 1: 1: 4 (T1), 1: 1: 6 (T2) and 1: 1: 8 (T3) (cement: lime : sand, dry bulk materials). The mortars were characterized in the fresh and hardened states and submitted to rheolog ical tests using the rotational rheometry and squeeze-flow techniques in addition to the sprayed test. After at least 28 days of curing, the coatings were characterized by tensile strength and permeability tests by the pipe method. The results showed that the sands presented significant differences regarding shape parameters (shape, roundness and sphericity) and CG-APR, CG-VSI 1, CG-VSI and CG-CONV 1 compositions were considered as well rounded and CG- CONV as rounded. Considering the squeeze-flow tests, there was influence of the granulometric composition on the mortars, since those produced with the thicker compositions showed to be more rigid, producing smaller deformations and with high loads of application. It can be inferred that the form factor generates influence in the resistance to the flow that contain grains with irregular forms and with rough surfaces. The results of rotational rheometry showed that the snads influenced the rheological parameters analyzed. It was observed that the main factors that influenced significantly the rheological behavior of the projection mortars were the parameters of form and granulometry of the aggregates, incorporated air and mass density. The tensile strength and permeability tests by the pipe method performed on the coatings produced showed significant influence of the shape parameters, particle size and dosage of the analyzed mortars. In this way, rheological parameters can be drawn which are: usable range form factor (rough and polished to polished, rounded and of low sphericity), usable range granulometric composition (aggregates with higher percentage of fines in the sieve # 0.6mm) and viscosity apparent between 14 to 28 Pa.s for polished grains and 16 to 48 Pa.s. for rough and polished grains
This study emphasize the influence of aggregate shape parameters on the mix design of sprayed mortars. The main objective of this work is to determine the parameters of projectability through the analysis of the form factor of the sands and rheology for the mix design of mortars of coatings. The experimental program consisted of the selection of three types of sands, one river quartz (APR), and two crusher of basaltic origin, one crushed by the vertical shaft impactor system (VSI) and the other crushed by the impact crusher system CONV). Fi ve compositions were produced, CG-APR, CG-VSI, CG-CON V, CG-VSI 1 and CG-CONV 1, the last two of which were corrected with CG-APR, aiming to overcome the demarcation of fines from the crushed sands. The physical characterization and shape parameters of the sands were performed through tests prescribed by the Brazilian standards and morphological analysis and image acquisition by the stereoscopic loupe and subsequent treatment of them using the ImageJ software. 15 means of sprayed mortars were made using the compositions in three different mix design, which are: 1: 1: 4 (T1), 1: 1: 6 (T2) and 1: 1: 8 (T3) (cement: lime : sand, dry bulk materials). The mortars were characterized in the fresh and hardened states and submitted to rheolog ical tests using the rotational rheometry and squeeze-flow techniques in addition to the sprayed test. After at least 28 days of curing, the coatings were characterized by tensile strength and permeability tests by the pipe method. The results showed that the sands presented significant differences regarding shape parameters (shape, roundness and sphericity) and CG-APR, CG-VSI 1, CG-VSI and CG-CONV 1 compositions were considered as well rounded and CG- CONV as rounded. Considering the squeeze-flow tests, there was influence of the granulometric composition on the mortars, since those produced with the thicker compositions showed to be more rigid, producing smaller deformations and with high loads of application. It can be inferred that the form factor generates influence in the resistance to the flow that contain grains with irregular forms and with rough surfaces. The results of rotational rheometry showed that the snads influenced the rheological parameters analyzed. It was observed that the main factors that influenced significantly the rheological behavior of the projection mortars were the parameters of form and granulometry of the aggregates, incorporated air and mass density. The tensile strength and permeability tests by the pipe method performed on the coatings produced showed significant influence of the shape parameters, particle size and dosage of the analyzed mortars. In this way, rheological parameters can be drawn which are: usable range form factor (rough and polished to polished, rounded and of low sphericity), usable range granulometric composition (aggregates with higher percentage of fines in the sieve # 0.6mm) and viscosity apparent between 14 to 28 Pa.s for polished grains and 16 to 48 Pa.s. for rough and polished grains
Abstract
Descrição
Tese de doutorado apresentada ao Programa de Pós-
Graduação em Engenharia Civil: Construção e Infraestrutura
da Universidade Federal do Rio Grande do Sul, como parte
dos requisitos para obtenção do título de Doutor em
Engenharia na modalidade Acadêmico.
Orientação: Profa. Dra. Angela Borges Masuero.
Palavras-chave
Reologia, Argamassa de projeção, Fator forma, Composição granulométrica
Citação
MELLO, C. W. de. Influência dos parâmetros de forma do agregado na formulação de argamassas de projeção. 2018. 208 p. Tese (Doutorado em Engenharia) - Escola de Engenharia, Programa de Pós-Graduação em Engenharia Civil: Construção e Infraestrutura, UFRGS, Porto
Alegre, 2018