huangyhg

spalled brick directly above steel relieving angle
i have a 40 year old concrete framed building with brick face and six inch block backup. brick over windows is supported by concrete lintels that extend from the spandrel beams. the adjacent brick beyond the windows sits on steel relieving angles bolted to spandrels at the same elevation as the concrete lintels. the brick directly over the relieving angles is spalled. what is causing this and can it be repaired?
possible moisture being trapped behind the brick and wicking through the brick or mortar joint. are there brick vent holes? not sure where you're located but could be subject to freeze-thaw and with the trapped moisture, the brick surface has exfoliated. spalled brick is usually indicative of a water/vapour/moisture problem. it's necessary to determine the source.
dik
i would suggest the same thing as dik. look for moisture as the root cause.
spalling is caused by moisture entrapment, and is especially sensitive in free-thaw areas as mentioned. another factor leading to spalling is low porosity, which in some areas is difficult to avoid.
i don't know of ways to repair spalling brick once they're in place. you may be able to paint them to prevent further spalling by minimizing moisture soakage.
i should also point out that coating them may not help at all. it is difficult to get water out of brick, and you may see spalling even after coating.
macmet - i was wondering if the sealing over the brick will envelope any existing moisture that is currently in brick that may dry out?
it might, that's what i meant when i said it might still spall even after coating. it is difficult to eliminate moisture held within bricks.
how bad is the spalling? is your concern structural or cosmetic?
there really isnt any way to keep all the water out of the brick, but a siloxane water repellant is a good idea. it breathes so moisture can exit, and it will do as good or better as anything else for keeping moisture out. it is really good stuff.
it is also possible the reason for the spalling is rust on the steel angles. rust basicly expands the steel, and the pressure behind or below the brick can cause spalling. a common solution would be to remove the brick, clean and coat the angle with rust preventive coating, replace the spalled brick, and apply water repellant.
another possibility might be that the weep holes or vents are either partially or completely filled with mortar or other debris. as a result, the lower brick may become saturated and then freeze thaw will spall the face of the brick.
it could also be that someone caulked along the line of the weep holes. everytime, i think that i have seen it all, i will discover another amazement.

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