Effect of lime on stabilization of phyllite clays

• First report on the stabilization of phyllite clays using lime
• Effect of lime addition at 3–7 wt.% on physical properties of phyllite clays
• Stabilization of phyllite clay using 3 wt.% lime improves capacity amble of the soil
• Use of phyllite clay–lime mixtures for earth construction, such as road subgrade
• Addition of lime to phyllite clay leads to a reduction in its plasticity index

This paper represents a new advance in the study of engineering properties and material applications of phyllite clays. Considering their potential use as construction materials for structures subjected to low stress levels, this laboratory research investigated the stabilization and improvement in engineering properties of a Spanish phyllite clay achieved by the addition of 3, 5 and 7 wt.% lime. Geotechnical properties investigated include the consistency limits, compaction, California Bearing Ratio, swelling potential and water-permeability. The phyllite clay–lime mixtures had good compaction properties and very to extremely low permeability-coefficient values, with a semi-logarithmic correlation between increasing permeability and increasing proportion of lime additive. The addition of 3 wt.% lime was sufficient to reach the index of capacity amble specified in the Sheet of Technical General Prescriptions for Works of Roads and Bridges PG–3 (Spanish Highways Agency, 2008), significantly reducing the plasticity index value, with the compacted mixture undergoing no swelling under soakage. The required pavement thicknesses for the raw phyllite–clay material and the phyllite clay–lime mixtures are compared and discussed. Potential applications for phyllite clay–lime mixtures include for pavements/road subgrade, earth construction, building materials and for impermeabilization purposes.