Property evaluation of beachrock based on field investigation in Okinawa Island, Japan

摘要

Beachrock is a coastal deposit with calcium carbonate and/or silica cement in the tidal zone of sandy beaches. Considering the application of man-made beachrock to preserve submerged-looking islands, we performed a literature survey and a field investigation to understand essential beachrock characteristics.We found that 90% of beachrocks worldwide were distributed within latitude of approximately 40 degrees north of the southern circle. It was also found that beachrock formed from several decades ago to around 7350 years ago. Furthermore, the main elements in beachrock worldwide differed. The beachrock in Okinawa, Japan mainly consisted of Ca and C. The unconfined compression strength, qu, was from 5.63 to 57.80MPa. The relation between qu and formative age, t, was qu=0.0141t. From these results, we obtained a wealth of data to build man-made beachrock.