Correlação de valores de tenacidade do concreto reforçado com fibras de aço obtidos pela ASTM C1609:2012 E EN 14651:2007

Abstract

The objective of this work is to experimentally analyze the toughness measurement of steel reinforced concrete samples according to the recommendations of international standards ASTM C1609:2012 and EN 14651:2007 and then compare such methodologies. It is also desired to evaluate the influence of the compressive strength and the fiber content in the toughness measurement. Two concrete matrices with compressive strength of 20 MPa (C20) and 40 MPa (C40) were used, without fibers and with three dosages of fibers corresponding to 30 kg/m³, 40 kg/m³ and 50 kg/m³. For the evaluation of the tenacity, 48 prismatic specimens and 64 cylindrical specimens were molded for the characterization of the composite by means of tests of compressive strength and tensile strength by diametrical compression. After the tests and results analysis, it is expected that the steel fibers give the concrete an increase in tensile strength in flexion. The results indicate that the increase of the CRFA toughness measure was higher when the fiber content in the composite was increased, when compared to the change in the compressive strength of the cementitious matrix. In addition, in comparison to the results obtained by these tests, greater measures of toughness are observed for the method proposed by ASTM C1609:2012, however the values found by standard EN 14651:2007 presented lower standard deviation. Such behavior is explained because the formation of the first crack occurs in the region of the notch plane, reducing energy dissipation in the specimen. Finally, it is concluded that there is a correlation between the methods of approximately 0.50 and 0.36 for the resistance class C20 and C40, respectively. This is strongly dependent on the volume of fibers added.