scholarly works

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Pedo-geotechnical evaluation of subgrade soils along failed Ago-Iwoye/Ilisan road, part of southwestern Nigeria
(Taylor& Francis ltd, 2024-03) Adebisi, N. O.; Ariyo, S. O; Denis, K.; Olufemi, S. T.; Akintayo, F. O.; Oyebolu, O. O.; Frank, A. I
This study utilized the principles of soil mechanics and the physiograph concept to establish pedo-geotechnical patterns of natural soils for the design of pavement structure. A total of 60 disturbed and undisturbed subgrades were sampled from 10 locations at the SB segment, 10 locations through the TZ and 10 locations at the BC end. A series of specific gravity, grain-size distribution, consistency limits, compaction characteristics (unsoaked and soaked CBR) and shear strength parameters were performed. Field observation and test results revealed that the studied area consists of extensive sand, interposed with clayey sand bodies along the SB segment. Also, particles of various sizes at the TZ and heterogeneous sandy clay in the BC segment were noted. Soils from the TZ under soaked conditions have the highest CBR (80.0–88.1%), MDD (19.0–19.1 kN/m3) and the lowest OMC (10.2–10.5%) values. They also have the highest cohesive strength (72.0–80.0 kN/m2) and angle of internal friction (14°−16°). Comparison among properties revealed that soils from the SB area especially, the TZ have much higher subgrade ratings compared to the soils from the BC terrain. The result revealed that the physiography factors affect the performance of the entire pavement structure.
Stabilisation of the Lagos-Ibadan expressway’s Ojoo-Iwo Road section using geosynthetics
(Department of civil engineering university of Ibadan and society of cement and concreteresearchers in Nigeria, 2024) Ibrahim, M. O.; Akintayo, F. O.
Road performance and longevity are greatly enhanced by geosynthetics. It carries out a number of functions, including reinforcement, stability, separation, fluid barrier, drainage, and filtration, to improve their use on road pavement. Geosynthetic materials were introduced to some sections of the subbase layer of the Lagos- Ibadan expressway to enhance the overall performance of the pavement. Soil samples were collected at a burrow pit at km 90 of the Lagos-Ibadan Expressway. The contractor handling the Ojoo-Iwo road segment of the expressway provided the geosynthetic materials employed in the study. The natural moisture content of the soil, sieve analysis, Atterberg limits, optimum moisture content, Maximum Dry Density (MDD), and California Bearing Ratio (CBR) were determined using standard procedures. The soil is gapped-graded, sandy-gravel, and has a plasticity index of 8%. The natural and stabilized soils have corresponding MDDs of 2040 and 1960 kg/m3. After the geosynthetic materials were added to the subbase layer, the soil sample’s CBR rose from 26% to 30%.