HUMBERTO R. ROMAN and FRANCISCO T. NEGREIROS Universidade Federal de Santa Catarina, Brazil
The paper describes part of a research project into the addition of either pulverized fuel ash (pfa) or furnace-bottom ash (fba) to clay for brick production. The ashes are wastes from a coal-burning power station in Santa Catarina state. The clay was obtained from a brickyard near the station. Three types of specimens were made: clay alone and clay plus the additives. The proportion of ash in the mixtures was varied from 0 to 50% by weight. The making moisture content, the firing temperature and cycle were other variables studied. The mechanical and physical characteristics observed were: drying rate, compressive strength, water absorption, suction rate and apparent density. The main conclusions are: the reduction in drying and firing shrinkage may be important to obtain better control of the shape and homogeneity of dimensions: natural drying, normally used by the brickyards in the region, takes a shorter time with the addition of ash; the compressive strengths obtained are well inside the specifications of the Brazilian standards: the lower density allows light bricks to be made. The addition of either pfa or fba to the clay may be helpful to prevent environmental pollution by coal ashes and also to obtain bricks of good quality.