Fundamental Study on the Application of Oyster Shell as an Aggregate for Concrete in Coastal/Marine Structures

This study uses oyster shells as an aggregate substitute for marine concrete structures. The initial strength of concrete according to the proper particle size composition of the crushed oyster shell was experimentally analyzed. The particle size of the crushed oyster shell obtained through the shredder is out of the range of general aggregates' standard particle size curve because the ratio of 5 mm or less exceeds 50%. It was confirmed that if less than 5 mm was left abroad, it was within the range of the standard particle size curve, and only these were applied as thick aggregate substitutes. The crushed oyster shells impair workability due to their relatively high absorption rate. This study attempted to overcome poor workability by using two methods: using the crushed oyster shells in a saturated-surface-dry (SSD) state and adding an air entraining agent (AE). The SSD case showed that the slump increased, but the strength decreased by about 40%. The AE added case showed a slight decrease in strength while the slump more than doubled.