Geotechnical Investigation of Residual Soils Along Ola-Adua Road, Ibadan, Southwest,nigeria

This study investigate the geotechnical properties of subsoils behind Apete Garage Ola-Adura road, Ibadan, to assess its contribution to road construction. Field laboratory tests, including natural moisture content, sieve analysis, specific gravity, Atterberg limits, compaction, and California bearing ratio (CBR), were conducted on soil samples collected at 10 locations. These tests aimed to determine the soils suitability for road construction, focusing on compaction properties, bearing capacity, and moisture retention. Moisture content across the locations ranged from 2.1% to 70%. The extremely high moisture content at SL1 (70%). In contrast, SL2 (2.1%) and SL7 (2.8%) showed the lowest moisture content. The particle size distribution analysis revealed that SL2 (83.16%) and SL5 (87.44%) add a well graded gravelly composition, conversely, SL1 (24.52% fines) and SL9 (10.03% fines) contained higher proportions of fines. Specific gravity values ranged from 2.2to 2.4. Soils with lower Gs values, such as SL3, SL5 and SL7, indicated the presence of organic material, leading to reduced load bearing capacity and potential for compaction issues. The average specific gravity of 2.33 suggests a mix of sandy or silty soils across most locations. The plasticity index (PI) varied across the samples, with SL1, SL2, and SL6 having low PI values (