MAURO SASSU University of Pisa, Italy

The residual stresses arising in solid clay bricks during firing and cooling have been studied utilizing three different extensometer techniques: the complete cutting method to reveal the overall distribution of stresses on the main brick surfaces; the hole drilling technique prescribed by ASTM guidelines for point measurements of surface stress; and the ring core measurements, usually performed for determining the internal distribution of residual stresses in steel samples. The measurements reveal that the thermal processes cause traction states generally high enough to give rise to the cracking patterns typically seen on the surface of bricks. Moreover, the possibility emerges of applying such tests to the quality control of bricks subjected to thermal actions during the various stages of their manufacture.