This procedure is a method for evaluating the carbonation resistance of concrete using test conditions that accelerate the rate of carbonation. After a period of preconditioning, the test is carried out under controlled exposure conditions using an increased level of carbon dioxide. NOTE The test under reference conditions takes a minimum of 112 days comprising a minimum age of the specimen prior to conditioning of 28 days, a minimum conditioning period of 14 days and an exposure to increased carbon dioxide levels of 70 days. This procedure is not a method for the determination of carbonation depths in existing concrete structures.