CORRELATION BETWEEN POROUS STRUCTURE AND FRACTURE-STRESS FOR METALLURGICAL COKE

Various samples of coke have been characterized by diametral compressi on and the geometry of the porous network has been analysed in terms o f fractal structure. It is found that the coke studied exhibits a frac tal behaviour on at least two decades. Diametral compression test lead s to two different ways of breaking: brittle fracture, and in some cas es complex fracture. As expected, the fracture stress is not linked wi th the fractal dimension in case of brittle fracture, but with the mea n size of the largest pores. In case of complex loading conditions, th e fracture strength is linked with the fractal dimension. The models o f Cook and of Anderson, which integrate fractal description of porous materials in Griffith's theory, do not seem to be valid concerning cok e material. The present approach of characterising the porous structur e of coke by the fractal dimension seems adapted to explain coke stren gth, especially under complex stress conditions, but should be extende d to an increased number of coke type samples.