Aggregate size effect on the mineralogical composition and microstructure of lime-treated soil (extended abstract)

Aggregate size effect has been proven to be a significant factor influencing the hydro-mechanical behaviour of lime treated soils. The main objective of this work is to give interpretations on the different behaviours of lime treated soil with various aggregate sizes from mineralogical analysis. Three soil powders with different maximum aggregate sizes (D_max = 5, 1 and 0.4 mm) were prepared before 2% lime treatment. X-ray diffraction (XRD), environmental scanning electron microscope (ESEM) coupled with chemical analysis using energy dispersive X-ray spectrometry (EDX) and mercury intrusion porosimetry (MIP) were used to analyse untreated and treated samples at various curing times. The results indicated that crystallized C-S-H was detected in the lime-treated soil prepared with large aggregates (D_max = 5 mm) after one year curing. This is due to the calcium-rich areas generated when lime is mixed with large aggregates. However, results of the treated soil prepared with small aggregates (D_max = 0.4 mm) suggested that nanocrystallized C-S-H or poorly-crystallized C-S-H occurred because of the thin lime layer on the large surface of small aggregates.