Evaluation of Strength Properties and Performance Characteristics of Lime-Quarry Dust, Cement Stabilized Inorganic Clay for Sub-Base Pavement

This research worked on the improvement of inorganic clay for use as a sub-base material in flexible pavement through stabilization with lime-quarry dust and cement mix. The research focused on evaluation of change in key geotechnical parameters; Optimum Moisture Content, Maximum dry density, Atterberg limit, Compaction characteristics, Unconfined compressive strength, Permeability and Shear Strength of the Inorganic clay.

The soil sample were mixed at varying proportions 2% - 8% lime, 15% - 30% quarry dust and 2% - 8% cement. Standard laboratory tests including particle size analysis, Atterberg limits, Specific gravity, proctor compaction, California bearing ratio, Unconfine compressive strength test and permeability test were conducted in accordance to relevant ASTM standard.

The stabilised mixes show optimal at 6% lime + 20% quarry dust and 6% cement mix. Lime + quarry dust mixes reduced plasticity index from 8.6% to 2.6% while cement mix reduced the plasticity index from 19.4% to 9.5%. The MDD value decreases from 1.74g/cm³ to 1.65g/cm³ while the OMC increases which is typical for lime stabilization. For the cement mix, the OMC decreases while the MDD decreased slightly. The UCS increases for both stabilisers with curing time with 866.1kN/m² at 28 days for lime + quarry dust mix and 1069.9kN/m² for the cement mix and the CBR values increases for both stabilisers showing enhancement in strength which meet up with sub-base pavement requirement.

Based on this work, it is concluded that lime-quarry dust stabilisation enhances the geotechnical performance of inorganic clay offering a cost effective and environmentally sustainable alternative to cement. Therefore, lime-quarry dust blends are recommended for use in road construction projects involving clayey soils.