Pavement dimensioning with and on lateritic materials of the Mbu–Baforchu area

Abstract

The present study was conducted on lateritic sub-grade soils with the pavement structure built using lateritic materials. The objective of this work was to characterize the lateritic materials and obtain a correlation between the modulus of elasticity (E dyn) and the Californian bearing ratio (CBR) around the Mbu-Baforchu area in a bid to dimension a second access highway to the city of Bamenda. Identification tests (water content, particle size analysis, Atterberg limits) and mechanical characteristics tests (Modified Proctor, CBR and simple compression) were carried out on soil samples taken from the field. The CBR results were variable with values between 32 and 49 for burrow materials, while those for sub-grade vary between 6.5 and 14.4. A regression equation between the E dyn and CBR for the burrow material gave E dyn = 155.8exp (0.0541CBR) with a regression coefficient of 0.9599 while that for the sub-grade material was E dyn = 69.064exp (0.0706CBR) with a regression coefficient of 0.9295. The burrow and sub-grade soils fall within the S3 and S5 soil classes respectively. The HRB classification pits the burrow materials in the A-2 class with a group indices varying between 0 and 6, which describes them as a clayey loamy soils with (compressible nodular silty sands), while the sub-grade soils falls in the A-7-5 class and having variable group indices (12-20), thereby characterizing them as inorganic clays of high plasticity. The pavement structure designed for consists of a bituminous cover of 5 cm, a base course of 20 cm and a sub-base course of 20 cm. The pavement structure can carry a traffic loading of up to 3000 vehicles per day, inducing stresses and deflections within the pavement structure which are lower than their required permissible values. With ε t = − 14.5 μdef, ε t, perm = 62.8 μdef for the riding surface; σ t = − 0.118 MPa with σ t, perm = 0.427 MPa representing the permissible value for the base layer and ε z = 103.8 μdef, ε z, perm = 487.3 μdef for the sub-base layer; which reassures us that the pavement structure is durable.

Petrographical and geomechanical assessment of Widikum and its surroundings’ geological formations (North-West Cameroon) as construction materials

“…MB1 has a high bulk density (2.91 g/cm 3 ). This high value of density connects would be related to the density of olivine included between 3.2 and 3.6 g/cm 3 and that of pyroxenes (3.3 g/cm 3 ) its principal components. In addition, MB2 and MB3 have bulk density of 2.83 and 2.84 g/ cm 3 , respectively.…”

“…This high value of density connects would be related to the density of olivine included between 3.2 and 3.6 g/cm 3 and that of pyroxenes (3.3 g/cm 3 ) its principal components. In addition, MB2 and MB3 have bulk density of 2.83 and 2.84 g/ cm 3 , respectively. These values could be due to the density of micas which lies between 2.7 and 3.3 g/cm 3 and that of the average density of the minerals (2.65 g/cm 3 ) main constituent of granites [18].…”

“…According to the reference method EN 13383-2 (Table 6), it is described as excellent material. MB2 , MB3 and MB4 have a specific density ranging between 2.5 and 2.7 g/ cm 3 . From these, they are qualified as satisfactory materials.…”

“…Moreover, MB2 has a bulk density of 2.83 g/cm 3 , a specific density of 2.68 g/cm 3 . A Los Angeles abrasion value of 37.2; 35.1 and 29.7% and an aggregate crushing value of 15.9; 14.7; and 8.9% corresponding respectively to particles size classes 4/6.3; 6.3/10 and 10/14 mm.…”

“…According to the anthropic environment, it is necessary to investigate the concept of degradation of rocks in order to provide appropriate responses to the problems of conservation and restoration of these materials [2]. The road network can be taken as an indicator of the development of any society since it facilitates the movement of the humans and their thinks, therefore their having a direct impact on increase economic [3]. In this context, the road network has the obligation to ensure the adequate conditions of movement from the point of view of road safety, comfort and efficiency of transport [4].…”