Effects of metakaolin and zeolite on the dispersion properties and shear strength of dispersive clay soil

The current study used metakaolin and zeolite either separately or in combination at 0%, 2%, 4%, 6% and 8% of the soil weight to improve dispersive clay soil at optimal humidity levels. The samples were tested to determine the extent of change in the dispersion potential, as well as improvements in the shear strength of dispersive clay soil. The dispersive soil was obtained near the city of Ardakan in Iran and the extent of change in its soil dispersion potential was evaluated after 7 days of curing. The results of the pinhole test indicated that the addition of 2% zeolite plus 8% metakaolin to the soil considerably decreased the dispersion potential. Uniaxial testing after 7, 14 and 28 days of curing revealed that the UCS of the samples increased. The greatest increase was observed in samples containing 2% zeolite and 8% metakaolin after 28 days of curing. The direct shear test was carried out after 7, 14 and 28 days of curing on the unmodified soil and soil modified with optimal percentages of metakaolin and zeolite. The combined addition of zeolite and metakaolin was found to increase the shear strength parameters of the samples.