On the ICL test in soil stabilization

摘要

Some considerations upon the Initial Consumption of Lime (ICL) test, arisen from its use in the lime treatment of a pyroclastic soil, are presented. In the investigated material there are no ion-exchanging minerals, such as zeolites. Therefore when this soil comes into contact with lime, no ion exchange processes are expected, and lime consumption is due to pozzolanic reactions. The standard ICL test was performed on this material treated with different lime percentages, and pH value was checked for the following 14 days. Atomic absorption analyses of unconsumed lime have been performed on undersaturated lime solutions of the same soil. Data showed significant consumption of lime, due to pozzolanic reactions, as soon as lime comes into contact with the soil, influencing both Ca~(2+) concentration in solution and pH. Experimental data and theoretical considerations suggest that pH value could be not diagnostic in determining the amount of lime required to satisfy the soil affinity for lime if ion exchanging minerals were present. In fact when pozzolanic reactions develop in the very short term, pH measurement does not allow discerning the amount of lime consumed by pozzolanic reactions and by cation exchange.