The location of defects, including those found on the underside of the slab, should be marked on the site plan. Because the edges tend to break off, cracks appear wider at the surface level than below it. This difficulty is overcome by reporting the crack width at a depth 5 mm below the surface. If the deck is covered with a wearing course, such as asphalt, the condition of the concrete must be assessed from signs of deterioration, such as rust stains, cracks, water spots and efflorescence, on the underside of the slab. The distance between floor drains should be noted, as well as the condition of the drain pipes, the effectiveness of the slopes and the likelihood of puddle formation.
Expansion joints have to be carefully examined and, if defective, repair or replacement ordered.
This is quite often overlooked and the penetration of salt laden moisture seriously shortens the lifespan of the repaired deck. Of particular concern are the expansion joints over ledge beams, a location of structural importance. The observations noted on the site plan serve as the basis for developing a repair strategy. Delamination survey Delamination is the separation of the slab usually at the level of reinforcement in a plane roughly parallel to the upper surface, and is caused by corrosion of the steel. Whether visible on the surface or not, delaminations should be repaired as they indicate a high level of corrosion activity and may lead to significant structural weakening.