STICKY RICE SLURRY-MODIFIED LIME-METAKAOLIN STABILIZATION OF SILTY CLAY: MECHANICAL PERFORMANCE AND MICROSTRUCTURAL CHARACTERIZATION
Keywords:
Sticky rice slurry, Metakaolin, Lime, Silty clay, Unconfined compressive strength, MicrostructureAbstract
Lime-stabilized silty clays are widely used in subgrade construction and earthen heritage conservation, but their relatively slow strength development, susceptibility to wet-dry deterioration and limited long-term durability still constrain their broader engineering applications. In this study, a ternary binder consisting of sticky rice (SR) slurry, metakaolin (MK) and hydrated lime was formulated to stabilize a low-plasticity silty clay, with the aim of exploiting both the pozzolanic reactivity of calcined kaolin and the biomolecular templating effect of amylopectin. A systematic series of unconfined compressive strength (UCS) tests was conducted on lime-soil (LS), metakaolin-lime-soil (ML) and sticky rice-metakaolin-lime-soil (SM) specimens with varying lime contents, metakaolin dosages, sticky rice concentrations and water-to-solid ratios, cured for 7, 28 and 90 days. The microstructural and mineralogical evolution of the stabilized matrix was characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD), and the internal water retention behavior was tracked throughout the curing period. The experimental results indicate that the optimum binder composition corresponds to 13% lime, 10% metakaolin and 3% sticky rice at a water-to-solid ratio of approximately 0.34, beyond which strength either plateaus or declines because of dilution or excess organic phase. Compared with conventional LS and ML systems, the SM specimens develop a denser and more homogeneous gel-rich microstructure, exhibit a more pronounced consumption of portlandite and a stronger amorphous hump associated with C-S-H and C-A-H, and retain internal moisture more effectively during curing. The synergetic interaction between the biopolymer network of sticky rice and the pozzolanic products of the lime-metakaolin system is identified as the principal mechanism underlying the strength enhancement, providing a sustainable and historically inspired stabilization route for silty clay.References
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