Influência da variação da velocidade de rotação e do tipo de cimento nas propriedades de argamassas de revestimento nos estados fresco e endurecido

Abstract

ResumoA etapa de mistura influencia as condições de execução do revestimento de argamassa, visto que desde o primeiro contato dos materiais sólidos com água uma série de eventos de aglomeração e desaglomeração no sistema é verificada. Acontece que durante o processamento das argamassas em obra a utilização de equipamentos com distintos mecanismos de mistura pode modificar o desempenho do sistema de revestimento. Este trabalho foi realizado com o objetivo de avaliar a influência da condição de mistura durante o processamento de argamassas aditivadas com incorporador de ar e formuladas com diferentes tipos de cimento. As misturas foram realizadas em um reômetro rotacional variando-se a velocidade de rotação, porém mantendo-se o tempo total de batimento. Reometria de mistura, ciclo de cisalhamento e teor de ar incorporado foram as propriedades avaliadas no estado fresco, enquanto porosidade, resistência mecânica, módulo de elasticidade e permeabilidade ao ar foram utilizados para avaliação do estado endurecido. Com base nos resultados obtidos pôde-se afirmar que a variação da velocidade de rotação e o tipo de cimento utilizado impactaram as propriedades das composições nos estados fresco e endurecido. Palavras-chave: argamassa, CPIIF, CPIII, energia de mistura, reômetro. Abstract The mixing stage is one of the most important step for the execution of the rendering mortar, since from the first contact of the solid materials with water a series of agglomeration and deagglomeration events in the system is verified. However, during the mortar processing in the buildings the use of different equipments, with distinct mixing concepts, makes this stage very uncontrolled. The main purpose of this work was to evaluate the influence of mixing condition during the processing of mortars with addition of air-entraining agent and formulated with different kind of

Utilization of discarded foundry sand (DFS) and inorganic waste from cellulose and paper industry for the manufacture of glass-ceramic materials

“…In the case of cellulose waste, CENIBRA Institute (Celulose Nipo-Brasileira) reported that, on average, each ton of cellulose produced generates 200 kg of solid waste, half of which is inorganic solid waste (dregs, grits, and lime mud) [4]. Some researches on waste from foundry industry have focused on DFSs due to their high volume (86% of generated waste [5]) and also to the various applications, such as utilization as aggregate in the manufacture of Portland cement concrete [6], and road paving [7,8]. Some works report the use of foundry waste, either without separation or mixed with other residues [9][10][11][12][13][14].…”

Characterization of fresh and hardened state properties of grouts for use in structural masonry

“…On the other hand, the hysteresis loop indicates that the finer particles and the surface areas tend to cause agglomeration in the cementitious system, which, with the increase of shear condition, were broken during an acceleration step imposed in the test. However, with deceleration, a re-agglomeration rate is not as pronounced as the disruption of the agglomerates [33].…”

“…The calculated area under the curves of Figure 4 indicates an estimative of the energy needed for the adequate mixing of each grout. The results are shown in Figure 5, with the graph produced as the function of the consumption of binder in each composition [33]. This comparative evaluation is valid only for the same mixing conditions applied in this work.…”