Engineering properties of residual soils in part of Southwestern Nigeria: implication for road foundation

Abstract

The impact of roads on the socioeconomic development and progress of any country cannot be quantified. A geotechnical investigation of subsoils along Isinbode-Ara road, stretching in southeastern to northwestern direction of 7 km distance within Ekiti State, Southwestern Nigeria, was carried out. This investigation follows the British Standard Institution, such as moisture content, particle size distribution, specific gravity, Atterberg limit, compaction, consolidation and California bearing ratio. Results of investigation showed that the moisture content, specific gravity, liquid limit, plastic limits and plasticity index ranged from 7.2-25.9%; 2.64-2.77; 24.0-61.1%; 19.2-26.2% to 4.35-38.90%, respectively. Grain size distribution showed the fine and coarser fractions range from 13.0-66.5% to 32.6-84.8%, respectively. The maximum dry density and its optimum moisture content ranged from 1.48-2.07 g/cm 3 to 11.3-30.3%, respectively. Soaked CBR results ranged from 3 to 44%. Two classes of subsoils, namely A-2-4 and A-2-6 (granular materials) and A-6 and A-7-6 (clayey soils), were identified and rendered suitable and unsuitable road construction materials, respectively. This investigation revealed that the subsoils are poor road construction materials due to its fine fractions and plasticities, which should be put into consideration during its foundation design and construction stages.

An Investigation Into the Cause of Road Failure Along Sagamu-papalanto Highway Southwestern Nigeria

“…This is linked to the geologic history and mineralogy of clays presents in the soils. The characteristics of clay soils are known by the physicochemical characteristics of the different constituents' minerals and by the relative proportions of the minerals present (Olo nyo et al 2019). The activity values from the studied soil ranges from 0.19-2.17 (Table 2) which indicate active to inactive clays.…”

“…7. The California bearing ratio is usually used in evaluating the soils strength of subgrade, subbase and base course as road construction materials (Wignall 1999;Adeyemi 2002;Adeyemi 2013;Olo nyo et al 2019). The CBR values for the sample locations is in the range of 3 -5% for base course, 4-8% for subbase course and 3-12% for subgrade (Table 2).…”

Evauation of road failure along an erosion prone highway in ogun state southwestern nigeria using integrated methods

“…This is linked to the geologic history and mineralogy of clays presents in the soils. The characteristics of clay soils are known by the physicochemical characteristics of the different constituents' minerals and by the relative proportions in which the minerals are present [4]. Underwood [57] proposed three classes of clay based on their activity which includes; the normal clays, active clays and inactive clays which ranges from 0.75 to 1.25, value greater than 1.25 and value less than 0.75 Table 4.…”

“…It has been shown from past records that loss several lives and properties abound resulting from road accidents. [4]. Highway pavements and foundation soils are inseparable duo toward the development of any country [5].…”

Geotechnical Characterization of the Subgrade on Some Rural Roads in Cross River State, Nigeria and the Influence of Geology

“…Soils from basement terrain always gives a pronounce upward concave shape in most part of the grain size distribution plot, that is tends towards the finer side; while soils from sediments gives a downward concave shape within the sand region grain size distribution plot that is the curve sags towards the coarse side. Olofinyo et al [15] in a study of engineering properties of residual soils in part of Southwestern Nigeria had sieve analysis plot of 16 soil samples, which are residual soils from Basement complex geology. 14 of the curves plotted with upward concave shape that has slight kinks towards the fine region of the sieve graph.…”