Mixing uniformity effect on the mechanical performance of lime-treated soil

This study investigates the influence of mixing uniformity (U) on the mechanical performance of lime-treated soils. A reproducible method was developed to prepare specimens with three uniformities. The U values are 91.2%, 77.6%, and 68.8% respectively, which was quantitatively assessed by the distribution pattern of low-density regions (lime) in X-CT images. The unconfined compressive strength (UCS) at 28 days and small strain shear modulus (Gmax) at 120 days were measured, showing respective values of 1.84, 1.32 and 1.25 MPa for UCS, and 226, 195 and 178 MPa for the Gmax, with U decreasing from 91.2% to 68.8%. This suggests that the higher uniformity enhances the soil's mechanical performance and exhibits less damaged particles after UCS testing. The lime distribution was visualized and quantified as spheres and throats. The sphere radius and throat length display clear normal distributions. The specimens with higher uniformity (U = 91.2%) exhibit a more concentrated distribution, with most connected spheres having an equivalent radius between 0.5 and 1 mm, and throat lengths mainly ranging from 2 to 3 mm. The mixing uniformity significantly influences the extent of pozzolanic reaction, thereby impacting structural integrity and the aggregate strength, consequently affecting macroscopic mechanical performance.