Why will concrete severely burn the skin? Years ago I ended up with third degree burns on my legs, though prior to that I had concrete on my legs many times and never was burned. I know that there are several concrete burn cases a year at most hospitals, but it is still not a common occurrence in the trade. When I warn people who are working with concrete they reply that they have had concrete all over them and never have been burned. Do concrete batches vary enough to make some concrete more caustic? What components in concrete cause it to act as a lye and give third-degree chemical burns? I would appreciate an answer on this, and feel that it would be valuable information to pass on to others in the concrete industry.
It is the sodium and potassium oxides from the cement which, in combination with water, form hydroxides that are primarily responsible. These hydroxides (also known as caustic soda or lye and caustic potash) aggressively react to dissolve animal or vegetable matter. Some cements have considerably less alkali than others mainly depending on the raw material used but there are few, if any, that do not contain some alkalies. Virtually all concrete can be expected to attack the skin; it is only the degree of attack that may vary, and this will depend on the presence of moisture and the length of exposure as well as the alkali content. That people have had concrete all over them and never have been burned is very likely true but it does not negate the fact that these alkalies do attack the skin. If the concrete is not in contact with the skin very long or if the concrete and the skin both dry out rather quickly, the attack might not be severe enough to cause trouble. Furthermore, concrete attack on a callused skin area might not be noted if the attack were brief enough not to eat all the way through the calluses. The best thing to do when the skin comes repeatedly into contact with fresh mortar or concrete is to dry it promptly with a towel or rag. At the end of the working period the area should be washed with water or dilute vinegar until the soapy feeling has gone. Repeated washing during the work period instead of trying to keep the skin dry may make the situation worse.