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Hourglass-shaped specimen: Compressive strength of concrete and mortar (numerical and experimental analyses)
| IBRACON Structures and Materials Journal
Hourglass-shaped specimen: Compressive strength of concrete and mortar (numerical and experimental analyses)
Ulisses Targino Bezerra
IFPB
Salustiano Souza Alves
IFPB
Normando Perazzo Barbosa
UFPB
Sandro Marden Torres
UFPB
Abstract
Cylindrical specimens whose diameter is equal to half its height have been used worldwide. The statistical scattering in experimental testing of cementitious materials is a phenomenon known in literature and one reason is linked to the geometry of the specimens, which implies the possibility of different failure modes. This paper shows the evaluation of an hourglass-shaped sample , in which the highest stress occurs at the centre of the specimen, with negligible influence of stress distribuition from its ends. An amount of 260 cylindrical and hourglass samples were tested, with varying water/cement ratio and age. FEM analyses showed that stress in the central part of the hourglass specimens is 2.25 higher than that present at its ends. Modes of failure occured in differente ways in cylindrical specimens, whereas only one mode of failure was verified in hourglass specimens. The cylindrical samples showed bimodal frequency distribution, demonstrating the influence of the central part (material properties) and of its ends (boundary conditions), while the hourglass displayed a Gaussian distribution.
Author Biographies
Ulisses Targino Bezerra, IFPB
Engenheiro Civil e Professor do IFPB na área de construção civil.