An attempt was made to investigate the suitability of sandstones quarry spoils from Amasiri, Southeastern Nigeria for use as subbase in highway construction. Fifteen samples were subjected to some geotechnical analysis using British standards. From the results, the plasticity indexes are lower than the maximum value of 25% recommended for sub-grade and lower than 12% maximum for use as sub-base materials for roads and bridges. The maximum dry density and optimum moisture content indicate that the soils are generally of good graded and sandy clay with plastic fines (material passing sieve No. 200 with value <20%) indicating that the soils can be used as filling and embankment materials. All the soil samples have California Bearing Ratio (CBR) values that meet Nigeria Federal Ministry of Works and Housing standards of 80 and 30% minimum for un-soaked and soaked CBR, respectively for both base course and sub base materials. The coefficient of consolidation further implies that any structures found on the soils may undergo differential settlement of small magnitude, which varies unpredictably. The cohesion values of the undrained triaxial compression test for the tested samples ranging from 120 to 142 kN/m2 and the angle of internal friction which ranged from 16 to 25° indicate that the construction materials are of low plasticity, shear strength and good bearing capacity. More specifically, internal friction angle keeps on increasing as the specific gravity increases. The spoils are adjudged suitable for sub grade, sub base and base course materials as they satisfy most of the requirements specified for road pavements in construction projects.

Keywords: Abakaliki Anticlinorium, Amasiri, highway, residual, settlement, plasticity