Beachrock is what has been naturally solidified with calcareous material from sand and gravel on the beach. It takes several hundred thousand years or more for sand and gravel to solidify into rock, but there are examples of beachrock in Japan that have solidified into rock in only a few decades. This means that if we succeed in developing a new technology for accelerated solidification of beachrock, we can expect to find applications in technologies for preventing beach erosion, controlling deterioration, and extending the lifetime of coastal concrete structures, and self-repairing cracks in rock and concrete structures.
The main factor that causes beachrock to solidify is thought to be precipitated salt due to evaporation of seawater. However, we believe that local microorganisms are accelerating the process of beach sand and gravel formation into rock. Calcium carbonate, the main cementing material of beachrock, is the main cementing material of sedimentary rock, which is environmentally friendly. At the same time, as studying the mechanism of beachrock solidification, we discovered microorganisms suitable for calcium carbonate precipitation around beachrock in Okinawa Prefecture, Japan, and developed a technology to solidify soil into something like rock or concrete in a relatively short time using these microorganisms. We have also applied this technology to coral sand on the coast of Okinawa Prefecture and confirmed its effectiveness.