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Seek professional medical attention without delay
When cement is dry it contains calcium oxide, which is not particularly dangerous. However, when water is added to cement, calcium hydroxide is formed, which is extremely alkaline with a pH of 12 to 13. Normal human skin has a pH of 5.5; therefore, wet cement can produce alkaline (caustic) skin burns which progress and get worse without more exposure. A worker may have wet concrete on his or her skin for hours without feeling any discomfort; however, the cement is damaging the skin microscopically. Early identification of changes to the skin is important so steps can be taken to treat the affected area.
Don’t assume the burn will not get worse. By the time a worker becomes aware of a burn, much damage has already occurred and further damage is difficult to stop.
Cement burns frequently produce discoloration of the skin, gradually changing to a deep purple-blue color, eventually progressing to painful burns, ulcerations and, in the worst cases, amputation. Some patients report red inflamed skin near the affected area followed by severe blistering. Cement burns can also lead to allergic dermatitis.
Wet concrete has additional characteristics that are harmful to human skin: hygroscopic (draws moisture from skin); abrasive (physically damages the skin surface, making it a less effective barrier); and contains sensitizing chemicals and metals, such as hexavalent chromium (can cause allergic contact dermatitis).
Once the eyes or areas of the skin have been directly exposed to wet concrete, immediate steps should be followed to slow the burning process:
Remove any contaminated clothing, being careful not to touch unexposed areas. Promptly rinse clothes in clean water.
Gently brush any dry chemicals off the skin and flush the affected area with clean running water for at least 20 minutes. To help neutralize the alkalinity, add vinegar, citrus or a buffer to the water.
If the eyes are involved, rinse eyes with clean water for 20 minutes.
Seek professional medical attention without delay. Provide the medical personnel with a product Material Safety Data Sheet (MSDS) and a Physician Alert brochure (available from The Center to Protect Workers’ Rights), which explains the skin hazards of concrete work.
Seek professional medical attention without delay
We had 3 guys taken to the hospital in the mid 70's .... from busting drill pipe apart.... after the shoe plugged .... they had to pull all at pipe from the well... even though they were wrapping it with burlap... the were still getting sprayed with the cement... one in serious condition
lol 
