ABSTRACT
Rigid pavements have gained popularity in the construction industry due to their durability and low lifecycle costs. However, the appropriate design of such pavements is crucial to ensure their longevity and performance. This study presents a detailed overview of the geotechnical investigation, Estimated Single Axle Load (ESAL), required for the redesigned of a deteriorated segment of Benin-Sapele by-pass pavement as a rigid pavement.
The investigation focuses on the assessment of the subgrade properties, identification of soil classifications, and determination of the ESAL parameters. Samples of soil were collected from different boreholes (drilling locations). These soil samples were taken to a laboratory. Various in-situ (on-site) and laboratory tests were conducted. The tests evaluated the soil's strength, plasticity, and compressibility characteristics. A traffic volume survey was conducted for seven consecutive days. The survey was done at 3-hour intervals. This data was used to estimate the design traffic load using the Equivalent Single Axle Load (ESAL) method.An Excel spreadsheet software was used to facilitate the analysis of the design process.
Based on the results from the geotechnical investigation, the sieve analysis result showed that was categorized as A-2 and A-2-4class soil. The usual types of significant constituent materials in an A-2-4 and A-2-6 soil classare Clayey soil, with goodsubgraderating in pavement designand asignificant level ofplasticity. The soil has a plasticity index of as 4.40% to 22.45%. The maximum Dry Density and Optimum Moisture Content were 1.86g/cm3, 1.68g/cm3, 1.87g/cm3, 1.91g/cm3 1.68g/cm3, 1.66g/cm3and13%,12.8%,13.1%,12.8% 13.5%forBH1,BH2,BH3, BH 4, BH 5andBH6respectively.The range of MDD, and OMC values depict an inorganic clayey soil, The California Bearing Ratio of the soil were values of 6.65%, 5.21% and 4.22%, 5.97% respectively, which do satisfy the FMWH minimumspecification for a good subgrade. However, soil sample at BH 5and 6 had a CBR value of4.22%, 3.07%which do not satisfy theFMWH specificationofasubgradematerial, hence the need for stabilization. The computed Estimated Single Axle Load (ESAL) for the projected year ranges from 2.5 x 106 to 4.6 x 106 single axle respectively. Hence, this study highlights the significance of a robust geotechnical investigation in the resign process of a rigid pavement.
