Application of solidified coal ash to sand compaction piles

We have been studying to use the solidified coal ash as a substitute for sand used in the sand compaction pile (SCP) construction process which is employed in the improvement of weak ground The particle size of the solidified coal ash is 5 to 20mm. We conducted the laboratory tests to examine the material properties as well as the in-situ tests at the practical construction. Results of our investigation confirmed the following: (1)Solidified coal ash (pellet material of particle sizes) made by adding cement to coal ash has a permeability coefficient of 1 x 10(-3)cm/s and internal friction angle of about 40 degrees when compacted with the standard compacting energy of 5.6cm.kgf/cm(3). Water permeability and mechanical properties are similar to those of sand. (2)Field verification test showed that weak sandy soil can be improved, with increased density, by placing piles of solidified coal ash. It was also verified that the SCP process using solidified coal ash satisfied the conventional design requirements. Work efficiency was found to decrease somewhat when using the solidified coal ash, as the material gives off fine particles due to vibration during the pile placing process.