抄録
The influence of cement in concrete on water quality and fish was studied experimentally. In the summer of 2001, an accident occurred where fish died in a torrent. It was said that the accident was caused by fresh concrete used for sabo structures partly running out into the torrent. That kind of accident has, however, not been reported to date in the field of sabo works. Mortar test pieces were used to study the influence of cement on water and fish in the experiments. The mortar test pieces raised the pH of water up to 11.54 at maximum. When cement was mixed into water directly, the pH of the water went up rapidly even if the quantity of the mixed cement was little, resulting in damage to the Japanese goldfish used in the test. A number of Japanese goldfish died when the pH of water exceeded 10.80. Air entraining agents do not affect the pH of water. Since there is a fear of cement greatly affecting the quality of water and the lives of fish, when concreting sabo structures, it is necessary to take great care to avoid fresh concrete running into the water and increasing its pH to the point of killing fish.
