CREEP!
Another revelation from the 1970′s (Just fun and interesting stuff!)
In high rise construction with brick veneer over reinforced concrete structure, horrible cracks began to develop in the brickwork. These cracks were horizontal, diagonal and vertical. Portions of veneer would begin to bulge outward. Brick would bulge outward past window frames. It was a pretty scary thing to see brick in this condition 15 floors up.
The concrete block back-up was installed on each concrete floor and went to the bottom of the next floor. The brickwork was continuous from the bottom of the building to the top. Of course, the brick and block were tied together with duro-wall or some other form of anchorage.
The cause turned out to be a concrete phenomenon called “creep”. Concrete shrinks as it cures and gives up its moisture. A high rise concrete structure looses some of it’s original height during this process. The brick and block are cured materials and will not shrink. Creep was literally crushing and pinching the masonry out of the structure.
What needed to change? They solved the problem by bolting support angles for the brick veneer at each floor. Both the brick and block stopped one bed joint short of the floor or angle above. This joint was filled with a mastic to serve as a compression joint.
