Experimental Investigation of the Confined Behavior of Dry and Wet High-Strength Concrete: Quasi Static Versus Dynamic Loading

Abstract

This paper presents an experimental investigation of the behavior of high-strength concrete (f c28 = 80 MPa) under very high pressure and quasi-static and dynamic loadings. Concrete specimen is inserted in an elastic, high-strength steel ring and subjected to an axial compression. In order to evaluate the confining pressure acting on concrete the ring is instrumented with multiple hoop strain gauges glued on its outer lateral surface. Dry and wet specimens are tested in both static and dynamic loadings in order to assess the influence of the free water content and the strain rate. Dynamic test are performed with a large diameter (80 mm) split Hopkinson pressure bar facility, adapted to test samples of large size (required for testing concrete material) at high stress levels. A strong effect of the free water content and the strain rate is observed in both deviatoric and volumetric behaviors of high-strength concrete. Both, the shear strength and volumetric stiffness increase with the increase of loading rate. One the other hand, free water has a beneficial effect on the volumetric stiffness and a strong negative influence on the deviatoric strength of high-strength concrete. The behavior of highstrength concrete was also compared to that of an ordinary concrete (f c28 = 30 MPa), tested in a similar experimental campaign. In both static and dynamic conditions, dry specimens of the two concretes reach approximately the same deviatoric stress level. However, when the specimens are saturated with free water, high-strength concrete exhibits a deviatoric strength much greater than ordinary concrete.

Strain-rate effects associated with the HJC concrete model

“…First, it appears that there is no universal strain-rate constant for a range of concrete materials. The publications by Piotrowska and Forquin [1] and Piotrowska et al [2] examined several different types of concrete, and the strain-rate constants were not consistent for the different materials. Most of the materials behaved in a manner similar to that considered here (with the modified model), but one of the materials (with limestone aggregate) behaved in a manner more like the original model.…”

“…3 Analysis of the strain-rate data Piotrowska and Forquin [1] and Piotrowska et al [2] recently presented experimental data for several different concrete materials subjected to a large range of strain rates and confining pressures. For this article the data for "siliceous aggregate" concrete [2] are analyzed.…”

“…In the original publication of the HJC model a small strain-rate effect was determined from test data at different strain rates, but for very low pressures. Recently, experimental strain-rate data have been presented for several different concrete materials [1,2], and the data are for a range of pressures. These data are exactly what are needed to determine an improved description of the strain-rate effect in concrete.…”

Residual strength of a high-strength concrete subjected to triaxial prestress

“…Since the initial work by Balmer, extensive work has been conducted to determine the triaxial properties of normal strength concrete (Imran and Pantazopoulou 1996;Malecot et al 2009;Forquin and Piotroska 2015;Vu et al 2008;Gabet et al 2007;Sfer et al 2002;Forquin et al 2009;Lu et al 2003;Forquin et al 2007;Bazant et al 1986;Chuan-Zhi et al 1987). The focuses of these efforts have been to discover the relationship between confining pressure and peak stress.…”

“…Many studies have been published using the GIGA press-located at the 3SR facility in France-to test concrete with confining pressures up to 850 MPa * (Malecot et al 2009;Forquin and Piotroska 2015;Vu et al 2008;Gabet et al 2008;Forquin et al Zaera 2009). Some alternative methods of triaxial compression use cubes that can be loaded independently in the three principal directions (Lu et al 2003).…”