What would cause brick facing to span from a highrise concrete frame building a couple of years after it was completed ?
This problem is most likely caused by differential movement. The brick can expand up to as much as 0.02 inch per story by moisture absorption. Meantime, the concrete behind it is undergoing both long term drying shrinkage and creep. The shrinkage and creep together could amount to as much as 0.23 inch per story making a possible combined difference in movement of 0.25 inch per story. The effect is severe compression on the brick, causing the facing to bow outward, crack and spall. The way to prevent the problem is to install a proper horizontal expansion joint in the facing at each floor slab. The joint should be sealed with a highly compressible sealant. Details are available from the Brick Institute of America,1750 Old Meadow Road, McLean, Virginia 22101.