A study on the application of copper slag as a sand substitute of sand compaction pile

Sand compaction pile method is a soil improvement method that a sand charge is introduced into the pipe, and the pipe is withdrawn part away while the sand pile is compacted and its diameter is enlarged. The sand used in this method should be good quality. In Korea, crushed stone and washed sea sand are used frequently in sand compaction pile method. However, the use of these materials is restricted because of environmental problem and deficiency of supply. In the copper smelting process, about 0.7 million tons of copper slag is produced in Korea. The range of particle size distribution of copper slag is from 0.15mm to 5mm, so it can be a substitute for sand, and the relatively high specific gravity compared with the sand, is its characteristics. Copper slag is hyaline and so environmentally stable that in foreign country, such as Japan, Germany and etc., it is widely used in harbor, revetment and offshore structure construction works. Therefore, in this study, the several laboratory tests were performed to evaluate the applicability of copper slag as a substitute for sand of SCP. From the mechanical property test, the characteristics of the sand and copper slag were compared and analyzed, and from laboratory model test, the strength of composite ground was compared and analyzed by monitoring the stress and ground settlement of clay, sand compaction pile and copper slag compaction pile.