IMPLICATIONS OF TOUGHENING OF CLAY BRICK ON PERFORMANCE

Bricks based on shale and alluvial clays were modified by additions of AFS 35 silica sand in attempts to improve toughness of the fired prod uct. These efforts were in response to the successful practices develo ped over the last few years to toughen alumina and dolomite refractori es using additions of zirconia of a particular particle size distribut ion and at a specific addition level. Sand additions were of interest in clay bricks due to the low cost of sand and due to the fact that it is a common accessory mineral in clays. The addition of sand was foun d to increase the work of fracture and impact resistance of clay brick . This was accomplished despite the expected decrease in density and s trength. Certain brick properties, such as chippage resistance, were i mproved by sand additions. However, additional tests showed that the b ricks with sand addition may exhibit decreased frost resistance. The r esults of this research have shown important implications of texture o n the performance of bricks in service. The performance sensitivity of clay bricks to sand additions may be greater than generally recognize d. Brick producers should consider use of control tests which are resp onsive to textural changes.