Correlation of damage after first cycle with overall fatigue resistance o refractory castable concrete

Cyclic thermal loads experienced in service by castable refractory concrete often cause fatigue failure. Displacement controlled cyclic fatigue measurements were performed on samples of corundum-andalusite refractory concrete at room temperature and at 1000 degrees C. The aim was to correlate the damage introduced in the first cycle (primary damage) and the overall fatigue performance. Damage was quantified by acoustic emission, dynamic Young's modulus and irreversible strains. Regarding the amplitude, three zones of fatigue resistance demonstrating specific degradation patterns were seen. The magnitude and microstructural type of primary damage correlates with the zones and can explain the patterns. Samples with higher primary damage demonstrate lower number of cycles to failure. Primary damage based limits seem to be able to determine the boundary loads for the zones of fatigue resistance. (C) 2019 Elsevier Ltd. All rights reserved.