AN OUNCE OF PREVENTION IS WORTH A POUND OF CURE
Alkali is a naturally occurring substance, or chemical found in the soil of the arid southwestern United States including Southern Utah. Masonry (brick, block, natural rock) is porous. It can absorb alkali when the soil around it gets wet, from rain or any type of landscape irrigation. As an example, consider the photograph above of the wall with the alkali (white staining) build up near the ground. The bottom of the wall is at ground level, actually just a few inches below. When the soil next to the wall gets wet, the water and the alkali in the soil mix together. Because the masonry is porous, it absorbs the solution in the same way that a sponge (or a paper towel) absorbs liquid. When the water evaporates, it leaves a very thin film of alkali on the block. Eventually the amount of alkali build up on the block becomes caustic. That means that the chemical buildup begins damaging the block. Eating it away like a cancer. This is a very slow process. It usually takes years for damage to show. However, it's all dependent upon the concentration of alkali in the soil. When you see alkali stains on the exposed side of a retaining wall, the wall either never had a moisture barrier or it has failed.
*The block in the first photo was damaged entirely by alkali.
*Next photo shows a wall that needs immediate treatment before it starts degrading.
*The next photo shows what alkali does to concrete.
*Is that snow in the last photo? Nope, it's alkali. What is it doing there? Rain, or water from some other source is drawing the alkali straight up out of the soil itself. That house is sitting on some extremely alkaline soil. If that was my house, I would be very concerned about the concrete slab and/or the foundation under the house.
ADDITIONAL INFORMATION ABOUT STAINED MASONRY
If you have alkali buildup on bricks and they are beginning to decay, they need to be treated right away. It is possible to replace individual bricks that are damaged. The problem is that manufacturers are constantly changing brick color and design. If the brick is more than 15 years old, it is probably no longer made. It is possible to find something close, but it detracts from the rest of the brick.
Alkali damage typically does not cause block walls to fall over. There is concrete and steel rebar inside the walls to disallow that from happening. However, the stains and wall damage are extremely unsightly and will devalue your property, not to mention, bother you daily. If the damage is bad enough, the wall may have to be demolished and rebuilt. That is very expensive because not only do you have to pay for a new wall, you have to pay to have the old one to be removed $$$$. An ounce of prevention is worth a pound of cure!
Hard water deposits typically occur on masonry because of lawn sprinkler overspray. Hard water deposits and alkali are two different things. Hard water is not caustic. Hard water build up is actually more difficult to remove than alkali. If you don't know which you have, call me and I will help you figure it out.