Swelling and Impervious Performance of Bentonite Mixed Soil Using Dehydrated Cake

In Japan, the function of embankment bodies has been impaired in the aging of small earth dams because of the piping phenomenon of the small earth dams’ bodies caused by torrential rain and cracking caused by earthquakes. Therefore, countermeasures and repair works are being promoted at various places in Japan. Basically, natural impervious soil such as cohesive soil is used as a part of a small earth dam body. However, in recent years, the shortage of high-quality natural impervious soil and destruction of nature by excavation are becoming important issue. Therefore, this study focused on dehydrated cakes generated from the crushed stone manufacturing process as an alternative material to the impervious soil. The dehydrated cake is composed of fine particles and has low water permeability. Also, the dehydrated cake is required to be actively used in terms of effective utilization of waste material. Furthermore, this study added bentonite to dehydrated cakes to improve water impermeability and prevent piping, and it was investigated the effects of bentonite type and addition ratio on the swelling performance of dehydrated cake and hydraulic conductivity. As the results, the condition with 10% sodium-type bentonite added to the dehydrated cake had the highest swelling ratio and satisfied the required strength for construction machinery. Furthermore, the permeability required as an impervious material was confirmed, and the swelling of the bentonite reduced the size of the holes in the specimen.