Sustainable subgrade improvement using limestone dust and sugarcane bagasse ash

The study investigated the suitability of Limestone Dust (LSD) and Sugarcane Bagasse Ash (SCBA) as stabilizer for the improvement of the geotechnical properties of Calabar subgrade soil. Limestone Dust (LSD) and Sugarcane Bagasse Ash (SCBA) wastes were employed as stand-alone stabilizers and in combination, to improve the geotechnical properties of Calabar subgrade soil. The soil was classified as clay with low plasticity using the USC-system and, A-6 under the AASHTO classification. The un-stabilized soil had a maximum dry density of 1.74 kg/m3 at an optimum moisture content of 24.5%, with a 48-hours soaked California Bearing Ratio (CBR) value of 6.92%, and, an unconfined compressive strength of 103.66 KN/m3. Stabilizers were added at 0% – 50% by weight of soil. Results showed a reduction in the swelling potential of the soil, improvements in compaction characteristics by a range of 4.3–9,8%, an increase in CBR by 50% -78.5%, unconfined compressive strength by 23.8%-38.1%, as well as improvements in shear strength, and secant modulus. It was observed that LSD as a stand-alone stabilizer and in combination with SCBA, showed better improvement compared to SCBA as a stand-alone stabilizer. It was concluded that a combination of limestone dust and sugarcane bagasse ash can be used for soil stabilization, contributing to the useful conversion of wastes and supporting the global advocacy for sustainable development in term of economic resource utilizatio