Sedimentary rocks including arsenic and pyrite such as mudstone in the Kazusa group are crushed and exposed to the atmosphere to oxidize and acidize them. The neutralization treatment was noticed as a method to prevent the contaminated soil from being contaminated by arsenic eluted. The method to estimate the amount of alkaline materials necessary for neutralization and the stability of the pH of the carbonated soil in the long term were examined. Since it is not realistic to confirm the behavior of pH by the long-term curing and many mix proportion tests, the possibility of the acidification test which is the test to promote the deterioration of the improved soil and the pH obtained by the repeated immersion curing are examined. It was found that the pH value of the acidification test was higher than that in the acidification test. It was suggested that the pH of the pH could be longer than the pH of the sample by the acidification test.
