Lime consumption of different clayey soils

• Assessing the lime consumption reveals the mechanisms of lime–clay mineral reaction.
• The kinetics of lime–clay reactions depend on the mineralogy of the clayey soils.
• Soils with different major clay minerals of kaolinite, illite and smectite are studied.
• Treatment with lime induces in all clayey soils the formation of Ca-hydrates.

This study focused on the lime consumption by 10% of lime treatment, of five soils containing different major clay minerals, kaolinite, illite, smectite–kaolinite, smectite–illite and smectite. Assessing the consumption of lime with respect to curing time, using an atomic absorption device, illustrates the lime–clay mineral reaction and the mechanisms involved in curing in the short- and long-term.X-ray diffraction and thermogravimetric analysis results show that clayey soils have different kinetic reactions depending on to their mineralogical composition, and that all soils consume the amount of lime added after a shorter or longer period of curing time. Two main reactions were assessed: the short-term reaction (cation exchange and flocculation) and the long-term reaction (pozzolanic reaction). These reactions are initiated due to the highly alkaline medium induced by the dissolution of lime in the water contained in the soil. The amount of lime consumed during the short-term reaction varies from nothing for kaolinite and maximum with sodium-smectite. The pozzolanic reaction present in all the clayey soils tested depends on the amount of lime available and is greatly accelerated by increasing the curing temperature from 20° to 50 °C. This reaction induces structural and mineralogical changes in the treated soils due to the newly formed calcium hydrates.