Study of mechanical properties and fracturing processes of carrara marble in dynamic Brazilian tests by two optical observation methods

Abstract

Strain rate affects both the mechanical properties and the fracturing processes of many materials. In the present study, some mechanical properties and fracturing processes - including the white patch development of Carrara marble subjected to quasi-static and dynamic Brazilian disc tests - are compared. The dynamic Brazilian disc tests are conducted by the split Hopkinson pressure bar (SHPB) along with a high-speed camera and dynamic data acquisition instrument. The indirect tensile strength of the marble shows a conspicuous strain rate dependence at a dynamic strain rate above 1 s-1, while it varies little in the quasi-static regime below 10-4 s-1c. Conspicuous microcracking zones in the form of white patches commonly appear much earlier before the development of macro-cracks. Such a white patch development and surface deformation, including the strain field on the surface of the specimen, are observed and analyzed by the image comparison method and the digital image correlation (DIC) method. © 2014 American Society of Civil Engineers.