Abstract
ABSTRACTThe objective of this paper is to evaluate a method based on image analysis to obtain shape parameters in crushed sand grains. There is no consensus about standards and rules for testing aggregates, the lack of methodology to prepare and conduct tests may produce incorrect results, which do not satisfactorily represent the aggregate characteristics. One way to perform these analyzes is the use of images obtained with magnifying glasses or similar equipment. To contribute to this, three experiments were prepared with samples of crushed sand from the city of Passo Fundo. The fixed and evaluated parameters were: samples preparation, zoom used for image acquisition and number of grains representative of the shape parameters. The results were statistically analyzed and significant differences were obtained to the shape factor regarding the fixed parameters, except for the number of grains needed to characterize it, which differs from the currently literature used by academic studies. According to this work it is possible to realize that it is necessary to standardize the tests for shape analysis to eliminate errors generated by the interpretation of incorrect results, which may have been generated by changes in the methodology for conducting the tests.
Highlights
Many studies have concluded that the aggregates used in concretes and mortars are not just inert materials
Compared with the aggregate obtained with crushing processes, natural sand has always been the main minute aggregate used for manufacturing mortars and concretes
Among the issues to be clarified for the understanding of aggregate grain shape are: if there is an effect regarding the type of sample preparation, which should be the increases used in image obtention and, especially, what would be the required number of grains to be used
Summary
Many studies have concluded that the aggregates used in concretes and mortars are not just inert materials. Among the various functions performed by them there are filling voids, contributing to a continuous grading curve of solids, restricting plastic shrinkage, etc.; there is a consensus that these aggregates are responsible for several of these properties, whether they are in fresh or hardened state These materials are present in significant proportions in concretes and mortars – in the latter they can correspond to up to 80% of the total mass of the mixture (CINCOTTO, CARNEIRO [1]). With the use of crushed sand, the study of shape and texture of large aggregates becomes more important to allow sorting, observing the changes and identifying the influence of form in the properties of materials produced with it. Among the issues to be clarified for the understanding of aggregate grain shape are: if there is an effect regarding the type of sample preparation, which should be the increases used in image obtention and, especially, what would be the required number of grains to be used
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