Abstract
There is a growing concern socially for the recycling of waste materials. In the geotechnical engineering community ground improvement by reusing wastes is expected to be developed. In the present study, laboratory tests have been conducted to examine the cementation of soil due to precipitates of calcium phosphate compounds by using waste oyster shell and phosphoric acid. Variations of Ca2+, PO43-, pH and EC in the solution were measured for the column test. It was found that the calcium phosphate compound was precipitated by reaction between the oyster shell powder and the phosphoric acid solution. According to the results of unconfined compression test and image observation, it was recognized that the strength of the sample was increased with an increase of curing day and the precipitated compounds were contributed to the increment in strength of the specimen. It was found that the strength of the specimen with the oyster mass mixing ratio not less than 1 and at the curing period of 10 days was above the target strength of 100 kN/m2.
