Experimental Studies and Modeling of the Concrete/Rock Interface


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Title: Experimental Studies and Modeling of the Concrete/Rock Interface

Author(s): J. Wang and A. K. Maji

Publication: Special Publication

Volume: 156


Appears on pages(s): 45-68

Keywords: electron microscopes; finite element method; fracture properties; microstructure; models; stresses; tension; Materials Research

Date: 9/1/1995

This study of the concrete/rock interface addresses primarily the interface of limestone and mortar (since no coarse aggregate was used in the mix) and, to a lesser extent, mortar and rock salt. Uniaxial tensile tests with closed-loop-control were used to determine the stress-crack opening displacement relationship in the softening regime. This relationship is proposed as the constitutive property in an interface cohesive zone model developed for interface fracture. The validity of such a model was investigated through testing and finite element analysis of compact tension specimens. A theoretical investigation of the effect of the complex singularity attributed to an interface crack was performed within the framework of the interface cohesive zone model. Although the theoretical analyses included only a semi-infinite geometry and was, therefore, limited in scope, it was found capable of addressing many of the characteristics of quasi-brittle fracture. Experimental tools used involved a scanning electron microscope to observe microscopic features of the interface that are responsible for strength and toughness. The electronic speckle pattern interferometry technique was used to evaluate pre-peak crack growth. Results indicate that the mechanisms responsible for strength and toughness at the interface are different and that the characteristics of the fracture at the interface is qualitatively similar to that of any other quasi-brittle material.