Maturation of loess treated with variable lime admixture: Pore space textural evolution and related phase changes
Abstract
Changes in the pore space of loess treated with 1%-8% of lime (CaO) and compacted in the laboratory were studied by the mercury intrusion porosimetry (MIP) over a long term period (1-360 days). The measurement of pH value was used to monitor the progress of pozzolanic reaction in curing time.
The development of the new mineral phases (calcium silicate hydrates, calcium aluminates hydrates and calcium aluminate carbonate hydrate) in the treated soil was investigated using X-Ray diffraction. The MIP indicated that 2% of CaO was sufficient for long term pozzolanic reaction.
The threshold value corresponded to the initial consumption of lime determined from the pH measurements. Although the pH value decreases with curing time, at pH higher than 11.7 the progressing pozzolanic reaction changes the voids of the lime treated soil.
Above 2% of CaO the macroporosity kept decreasing due to increasing mesoporosity for 360 curing days due to the new mineral phases. At 2% of CaO the decrease of the macroporosity are stopped at 120 days.
Below 2% of lime the changes of the macroporosity were detected during first 28 curing days due to the formation of portlandite and calcite.