CORAL SAND SOLIDIFICATION TEST THROUGH MICROBIAL CALCIUM CARBONATE PRECIPITATION USING PARARHODOBACTER SP.

Abstract

The coastal erosion has been a problem in associate with manmade construction. The maintenance
and management is expensive for repair and rebuild the coast. Compared to the concrete structure coral sand
solidification would considered to minimize cost. The present experimental study was conducted to coral sand
solidification through microbial carbonate precipitation (MCP) using Pararhodobacter sp. Ureolytic bacteria;
Pararhodobacter sp. was isolated from the beachrock in Nago, Okinawa, Japan. ZoBell2216E as a medium for
marine bacteria was used for the culture of the bacteria. Suitability for the use in MCP syringe test, growth
properties of the bacteria were observed in various cultural conditions. MCP sand solidification test was carried in
30mL Terumo syringe injected bacterial culture fluid. Strength of the specimen was measured by needle
penetration test. The maximum value of the absorbance at bacterial growth curve was constant if the added amount
of the medium is 100mL. The correlation coefficient of determination for absorbance measurements and viable
cell count measurements was obtained 0.5478. In MCP syringe test, pH of the specimen was decreased and Ca2+
concentration was increase with time. The estimated value of unconfined comprehensive strength (UCS) also
increased with time. The maximum value of UCS of the specimen was 12MPa. The estimated UCS values of the
specimen produced by sand solidification test for 14 days curing time have been achieved.