Scaling

Scaling is the delamination or disintegration of the upper portion of a PCC slab, and it can be caused by construction defects, material defects, or environmental factors. Construction defects include over-finishing, addition of water to the pavement surface during finishing, lack of curing, and attempted surface repairs of fresh concrete with mortar. Scaling due to construction defects generally occurs over a portion of a slab. Material defects include the inadequate air entrainment for the climate. Inadequate air entrainment usually occurs within an entire batch of concrete, and therefore, may affect several slabs. Environmental factors include freezing of concrete before adequate strength is gained, or thermal cycles from specific aircraft. Scaling may occur over an entire pavement in the case of freezing, or in isolated areas in the case of thermal effects.

Severity	Distress Example	Description
Low		Minimal loss of the surface paste that poses no FOD hazard. No FOD potential, limited to less than 1% of the slab area.
Medium		The loss of surface paste that poses some FOD potential including isolated fragments of loose mortar, exposure of the sides of coarse aggregate (Less than 1/4 of the width of coarse aggregate), or evidence of coarse aggregate coming loose from the surface. Surface paste loss is greater than 1% of the slab area but less than 10%.
High		High-severity scaling is associated with low durability concrete that will continue to pose a high FOD hazard. Normally the layer of the surface mortar is observable at the perimeter of the scaled area, and is likely to continue to delaminate or disintegrate due to environmental and other factors. Routine sweeping is not sufficient to avoid FOD issues, is an indication that high FOD hazard is present. Surface paste loss is greater than 10% of the slab area.