Influência do aditivo modificador de viscosidade e do fíler calcário no comportamento de pastas e argamassas de concreto auto-adensável

Abstract

The concrete self-compacting (CAA) was one of the greatest discoveries in concrete technology in recent decades. To be considered self-compacting, three properties must be achieved simultaneously: fluidity, cohesion and segregation resistance. The CAA can be shaped in various ways, eliminates defects caused by failure of concrete, as it has great ability to flow between the steel without segregation themselves by releasing the external vibration compaction, which reduces the manpower and accelerates construction. However, due to the high fluidity, undesirable effects such as segregation of coarse aggregate and water mixture can occur more easily. These effects can be controlled with the use of viscosity modifying admixture or mineral admixtures, such as limestone fillers. This study will evaluate comparatively the effectiveness of limestone fillers and viscosity modifying admixture in control of segregation and exudation of folders and mortar concrete self- compacting. Initially, there was a literature on the history, main properties and characteristics, advantages and disadvantages, constituent materials and concrete tests on self-compacting. The method of work was divided into three stages, first was made the characterization of materials used in this study, in the second step, tests were carried out scattering (mini-slump) and runoff (Marsh cone) into folders to determine the point of superplasticizer saturation and to assess the influence of limestone filler and viscosity modifying admixture in scattering and runoff of folders. In the third step, tests were carried out in mortars to determine the influence of limestone filler and viscosity modifying admixture in the spread and development of mechanical strength. It was observed that both the limestone fillers as the viscosity modifying admixture controlled exudation and segregation of the folders and mortar, however, the viscosity modifier additive caused incorporation of air in mortar, reducing the mechanical strength thereof. On the other hand, the limestone fillers improved the packaging of the grains, resulting in increased mechanical strength. In addition, the limestone fillers resulted in more homogeneous and cohesive pastes. With respect to costs, the mortar with the addition of limestone fillers have the same value (in R$/m³) that mortars with additive viscosity modifier.