The fracture behaviour of coal flyash compacts, in which interparticle
forces are relatively weak, is investigated. Notched and unnotched sp
ecimens of coal flyash compacts were tested to failure in flexure usin
g a test method developed in this report. The fracture toughness at fa
ilure, as calculated from linear elastic fracture mechanics (LEFM), ap
peared to be a constant of the material for a deep notch. Significant
weakening of the powder compact occurred in the presence of a crack. C
oal flyash compacts with a higher moisture content showed a degree of
plasticity; this is linked to an increase in the fracture toughness of
these compacts.