Determining the concrete stiffness matrix through ultrasonic testing

Abstract

ABSTRACT:The determination of the modulus tangent (E ci ) and of the modulus secant (E cs ) of the concrete can be done using compression test but, to be simpler, it is used relations with characteristic strength (f ck ). Relations are also used to determine the transversal modulus (G c ) and, in the case of the Poisson's ratio (), a fixed value 0.20 is established. The objective of this research was to evaluate the use of the ultrasonic propagation waves to determine these properties. For the tests were used specimens with f ck varying from 10 to 35 MPa. For the ultrasonic tests were used cylindrical and cubic specimens. The modulus of deformation obtained by ultrasound was statistically equivalent to the obtained by compression tests. The results of modules obtained using the relations with f ck was far away from those obtained by ultrasound or by compression tests. The Poisson's ratio obtained by ultrasound was superior to the fixed value. We can conclude that the concrete characterization by ultrasound is consistent and, to this characterization the cylindrical specimen, normally used to determine f ck , can be used. KEWORDS

Soil Elastic Modulus Determined by Ultrasound Tests

“…Other elastic constants, such as the shear modulus (G US ) and Poisson's ratio (u US ), can be determined using the matrices, S 44 and S 12 , respectively; however, this was not the focus of this study. Christoffel (Bucur, 2006) developed the theoretical equations above and these have already been applied for wood by other researchers (Gonçalves et al, 2011b(Gonçalves et al, , 2014Kohlhauser & Hellmich, 2012;Vázquez et al, 2015), in concrete (Gonçalves et al, 2011a) and stabilized soil (Ferreira et al, 2013;Hoffmann & Gonçalves, 2010;Milani, 2008).…”

“…The velocity of longitudinal and transverse ultrasonic waves is required when ultrasonic testing is used to determine elastic constants. The application of elasticity theory to the longitudinal and transverse velocities determines the elements of the stiffness matrix, which, after their inversion, result in the flexibility matrix and consequently, in the values of the elastic modulus, of shear and of the Poisson's ratio (Bucur, 2006;Bucur &Archer, 1984;Gonçalves et al, 2011aGonçalves et al, , 2014Kohlhauser & Hellmich 2012;Vázquez et al, 2015). Materials may present isotropic, anisotropic or orthotropic behavior, thus, it is necessary to know their elastic properties to determine the matrix (Bui & Morel, 2009;Bui et al, 2014b;Christ & Park, 2009;Ferreira et al, 2014;Maillard & Aubert, 2014;Miccoli et al, 2015;Pietruszczak & Krucinski, 1989).…”