Abstract
Twenty percent of slope surface soils show a very acidity below pH 4.9. There is a possibility of a gradually decreasing performance in slope protection work in such an acid ground. In this paper, sodding and a retaining wall deteriorated by soil acidification were reported in terms of damage circumstance, cause and countermeasures. Especially, a sample in which an acidic substance dissolved while causing slaking was investigated. The acidification speed changed uniquely with the grain size of the sample. The decrease in strength with soaking was independent of the pH of the pore water. The effects of the carbonationprocessing of the sample on compaction and strength properties were apparently recognized.