Calcium leaching mechanism of lime treated soil immersed in seawater

Abstract

The lime and the cement treated soil have been regarded as stable for a long time due to hydrate generated by pozzolanic reaction. As the treated soil is exposed to natural conditions, its strength would decrease by calcium leaching. In lowland having the thick alluvial clay deposit, the chemical soil treated method is often applied to improve the strength of soft clay ground. The lime treated soil applied to the base of a tidal river dike is deteriorating. It had been constructed in about twenty years ago and now appears to be muddy and leakage of river water. The treated soil is exposed to seawater in this area. This study considered mechanism of calcium leaching from the lime treated soil when it was immersed in seawater. Leaching tests were carried out to clear influences of the component of seawater on calcium leaching. Artificial seawater, NaCl, MgCl2, MgSO4 solutions were used in the test. Influence of NaCl on calcium leaching was very small. Magnesium containing in seawater reduced pH value of the solution-treated soil mixture. Calcium leaching was accelerated when magnesium concentration was higher. Magnesium was founded to be a main component to cause calcium leaching. © 2012 The Society of Materials Science, Japan.