Estudo da distribuição espacial da dureza em corpos de prova de concreto

Abstract

The study of crack formation and propagation processes in heterogeneous materials, with brittle or almost brittle behavior, such as concrete, rocks and ceramics, for example, is a constant subject of investigation, due to the complex mechanical behavior that these materials have. Through discontinuous computational mechanics, numerical simulations have a convenient structure to represent the disorder of the microstructure that of heterogeneous materials, through statistical models. However, the macroscopic response of these models is highly sensitive with regard to shapes, sizes and distribution of element properties, highlighting the need to correctly calibrate these parameters, thus enabling the formation and interaction between fractured elements to be described in a more accurate manner. true to what was found experimentally.This work sought to investigate spatial and non-spatial statistical parameters of the surface hardness of a C50 concrete, evaluating the influence of the maximum characteristic dimension of the coarse aggregate used and the state of stress acting on the samples, under the spatial distribution of the studied properties. The experimental analysis was carried out through the sclerometry test, carried out “in grid” on the surface of concrete specimens, produced with coarse aggregate of different granulometries (maximum characteristic dimension of 12.5 mm, 19 mm and 25 mm). In addition, the influence of the stress state to which a structure is constantly subjected to hardness values was verified, the investigation was carried out on the surfaces of cubic samples of C50 produced with crushed stone 1 (19 mm), subjected to an initial state without loading and with applied loading of 50%, 60% and 75% of the average tensile strength of the material. The results showed that the maximum characteristic dimension of the coarse aggregate did not influence the compressive strength of the concrete, and the Weibull-type probability distribution provided the best data fit for both dimensions of the coarse aggregate, but presenting different shape parameters for the distribution according to each household. The values of sclerometric indices were influenced by the load applied, with an increase of 20% for stresses greater than 50% of the average value of the material's breaking stress. However, the shape of the distribution and the parameters of the semivariogram were not sensitive in relation to the direction and the applied load.