Spalling of Brick
Spalling is generally a delamination and/or flaking at the surface of a material. Spalling of clay brick is shown in Figure SB-1. Spalling commonly begins when thin layers of the clay brick material have separated from the remainder of the brick. The separation occurs when a thin layer has been fractured from the brick by the repeated expansion of ice within the brick during the freeze-thaw cycle. The ice is a result of the freezing of excessive amounts of moisture within the brick material. The age of the spalling is often evidenced by the accumulation of dirt, biological growth, and/or wear on the fracture surfaces of the spalling. The progression of the spalling over the years is sometimes evidenced by the varying shades of these surface discolorations.
Excessive moisture in clay brick is commonly due to water infiltration through cracks in the brick work, absorption through the face of a porous brick material (often interior grade brick) or mortar joints, absorption of excessive amounts of water that are discharged onto the face of the brick work, water infiltration through joints and separations where the brick work abuts other materials, etc. Poorly manufactured brick are more susceptible to the absorption of surface water, and thus, spalling. See Figure SB-2 for spalling of brick under a leaking gutter.