The carbonation of a lime-treated soil: experimental approach

This paper presents an experimental study of the carbonation consequences on the macroscopic properties of a lime-treated silty soil. The classical cure in the lab confirms a slow increase in unconfined compressive strength (UCS) over time. Accelerated carbonation leads to a similar final value but the kinetic is different, showing a rapid increase of UCS then no further evolution with time. Samples stored outside also showed a rapid increase of the strength but the final UCS value is lower. Physico-chemical and microstructure analysis highlighted the rapid carbonation of Portlandite during carbonation. Carbonation was limited to the surface of the Portlandite nodules. In samples stored in lab, reaction of lime nodules with soil leads to formation of C–(A)–S–H gel. These two very different scenarios both led to a similar UCS increase, although at a different rate. On the contrary, samples stored outsides were shown to undergo carbonation of the C–(A)–S–H gel, hence explaining the lower increase in UCS.