Flaky surfaces of bricks is the best example of the term “spalling“. It is simply a type of damage that is caused by the freezing and thawing cycle of harsh cold weathers. Another way that causes spalling is when bricks are constantly exposed by moisture. You see, the melting, rainfall, and wet soil can easily saturate bricks. Over time, freezing temperatures can have a big impact since water slightly expands when it is frozen. When this cycle consistently repeats, the cracks tend to expand causing the bricks to eventually fall apart.
Preventing the effects of spalling is possible, and it starts from the beginning of construction. Bricks should be made durable, and it should be composed of hard and dense mixtures. When bricks fall apart, it’s most likely because it was made with softer bricks. This could happen by mistake or out of carelessness. Regardless, if bricks starts to deteriorate due to water damages the problem is probably not solely on bad brick.
Walls that are on the outside, needs to be constructed in a way that it keeps water out. This is especially true for retaining walls. One thing that is missing from this element is a cap or a coping in order to keep the rain out of the way.
They either consist of concrete, metal flashing, or special bricks in which case are angled to let water stream away from the wall. These are mostly found on the top of the wall where water first directly comes in contact with it. Perhaps a cap was present at the time being, but it was removed over time. Regardless, replacing it is highly suggested in order to prevent spalling.