Dual role of microcracks: toughening and degradation

Rao, Nagaraja GM and Murthy, CRL (2001) Dual role of microcracks: toughening and degradation. In: Canadian Geotechnical Journal, 38 (2). pp. 427-440.

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Abstract

One of the methods of improving the mechanical properties of ceramics is to introduce a defective structure that acts as a restraint for the propagation of cracks. In the present study a detailed investigation was carried out by introducing a defective structure in rock to determine if there is any improvement in properties similar to ceramics. Granite was chosen for the investigation, and the microcracks were introduced by a heating and cooling cycle. Uniaxial compression tests have shown that granite thermally treated to 200°C shows the highest strength, and the strength of granite treated to 400°C is comparable to that of unheated granite. Both ultrasonic images and acoustic-emission monitoring show that for thermally treated samples the stress-induced microcrack and macrocrack nucleation and their growth are retarded. The variations in mechanical properties are explained based on the concept of toughening and degradation. Uniaxial compression tests on unheated and thermally treated granite samples have clearly established the dual role of microcracks, which operate in the toughening and degradation mechanisms.

Item Type:	Journal Article
Publication:	Canadian Geotechnical Journal
Publisher:	National Research Council Canada
Additional Information:	Copyright of this article belongs to National Research Council Canada
Keywords:	Thermal treatment;Microcrack;Inelastic strain;Ultrasonic C-scan imaging;Acoustic emission;Toughening
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	13 Sep 2004
Last Modified:	19 Sep 2010 04:16
URI:	http://eprints.iisc.ac.in/id/eprint/1970

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