Stabilisation à la pouzzolane et à la géogrille des argiles latéritiques Des zones de Douala – Melong Et Bafang – Foumbot, Cameroun

Abstract

The stabilisation of lateritic clays (AL) with pozzolana (PZL) and geogrid (G) was evaluated through lithostabilisation and soil reinforcement techniques in the Douala - Melong and Bafang - Foumbot areas in Cameroon, with the aim of improving the use of clay materials in road construction. The natural materials collected and stabilised were submitted to identification and geotechnical characterisation tests. These tests focused on nature, compaction, elasticity and shear parameters. The studied superficial lateritic clays are very thick (1.95 - 7.00 m), fine (TF: 39 - 65 %) and plastic (IP: 20 - 36 %) materials. These lateritic clays are of low bearing capacity (CBR: 11 - 28 %) compared to pozzolans (CBR: 36 - 41 %). Natural lateritic clays are suitable for use as sub-base, whereas pozzolans are suitable for use as sub- base, despite their low maximum dry density values (DSM: 1.650 - 1.759). The addition of pozzolana fractions to these lateritic clays (ALP) results in a decrease in their plasticity (IP: 36 - 11 %) and effective cohesion (c’: 0.035 - 0.022 MPa), and, an increase in CBR bearing capacity (11 - 41%), uniaxial compressive strength (σc: 0.126 - 0.391 MPa), Young's modulus (E: 75.27 - 408.49 MPa) and internal friction angle (ϕ': 23 - 37°). Pozzolana stabilised materials (ALP) can be used for sub-base and base courses. For T1 traffic pavements, they can also be used as a base course. The reinforcement of these geogrid-stabilised materials (ALPG) is accompanied by an increase in CBR bearing capacity (11 - 63%), uniaxial compressive strength (σc: 0.126 - 0.942 MPa), Young's modulus (E: 75.27 - 943.28 MPa), angle of internal friction (ϕ': 23 - 42°) and effective cohesion (c': 0.035 - 0.112 MPa). This increase allows the deformation of these materials to be minimised once they have been implemented. ALPG mixes can be used as a sub-base and base course for pavements with traffic levels T1 to T3. Numerical analysis of the modelling of the behaviour of ALPG materials shows that the use of ALPG materials in pavement layers at thicknesses greater than that of the specimens is not disturbed, although this variation in thickness has led to a slight decrease in mechanical parameters. The economic analysis confirms that ALPG materials are viable in a natural setting unfavourable to conventional materials. Their implementation in the study area is less expensive than that of natural materials such as lateritic gravel and rock crushed stone.