抄録
In the oyster producing district, the shells are being crushed to maintain the capacity of dump yard. Though the crushed oyster shell has been diverted to feed, manure and soil conditioner from a past, the shell pieces are possible to also use as the construction materials.
The purpose of present study is to verify the usefulness of crushed oyster shell as subgrade materials by executing improvement of existing road. The construction work was carried out in March, 2002 and the widening subgrade (70m in length, 3.5m in width and 0.35m in thickness) containing crushed oyster shell was built under three mixing conditions. The surface treatment was immediately paved over the base course after base materials were compacted. Allowing passage of vehicles, we have recently investigated the deflection shape of road surface by using “falling weight deflectometer” (FWD). According to the relationship between the load and the detected deflections, the maximum deflection at loading point tended to decrease with an increase in service time. Particularly, CBR value estimated from the deflection (D1500) has exceeded an object level of improvement for section including the almost dried shell pieces. These results show that the crushed oyster shell can be effectively utilized as subgrade materials.
