  Refractory masonry (refractories) of industrial furnaces experience loads of
various nature during service. Microstructural aspects of failure in silica
refractories under monotonic and cyclic fatigue wedge splitting loading was
studied. Knoop hardness measurements assisted the analysis. Monotonic and
cyclic loading resulted in similar average strength with lower fracture energy
for the first. With similar average crack non-linearity and trans granular
failure, due to lower matrix damage and higher energy input the monotonic crack
follows preferably grain-matrix interfaces (lowest energy consuming route). In
cyclic mode, repeated loading increases energy dissipation. Within one loading
mode, the brittleness correlates with trans granular failure.
