TITLE:
Geotechnical and Thermo-Physical Characteristics of a Fine-Grained Lateritic Soil Excavated from a Road Construction Site: Experimental Study
AUTHORS:
Soumaïla Gandema, François Dabilgou, Marie Therese Marame Mbengue, Rimyalegdo Kiébré, Guillaume Zamantakonè Ki, Marcel Bawindsom Kébré, Adamah Messan
KEYWORDS:
Excavated Materials, Experimental Characterization, Sandy-Clay Soil, Road Earthworks, Sustainable Development
JOURNAL NAME:
Open Journal of Civil Engineering,
Vol.16 No.3,
September
23,
2026
ABSTRACT: The durability of road infrastructure in Sub-Saharan Africa represents a major challenge, exacerbated by growing climate hazards and the depletion of conventional materials. Road construction projects consume non-renewable natural resources such as lateritic gravels, as well as locally scarce resources such as water. In response to the need to preserve these resources, the valorization of local excavated materials—previously considered unsuitable for reuse—appears promising. This manuscript presents a comprehensive characterization of an excavated fine lateritic soil from a road construction site in Bassinko (Burkina Faso), with a view toward its reuse in earthworks. The objective is to evaluate its thermo-hydraulic and mechanical properties to provide a sustainable alternative to the exploitation of traditional lateritic borrow pits, which are becoming increasingly scarce. Experimental investigations on the material focused on determining its physical and morphological properties (particle density, Atterberg limits, methylene blue value, particle size distribution, Proctor characteristics), thermal conductivity (in dry and saturated states), the soil-water characteristic curve (SWCC), and mechanical bearing capacity (CBR/IPI). The results show that thermal conductivity is highly dependent on the degree of saturation, increasing from 0.458 W∙m−1∙K−1 in the dry state to 1.826 W∙m−1∙K−1 at saturation, illustrating the formation of aqueous thermal bridges. The analysis of the SWCC, modeled using the Van Genuchten equation, reveals high Van Genuchten modeling parameters
P
dry
and
P
sat
(1.85 MPa and 1.03 MPa, respectively), confirming a fine microporous structure. Although soaking causes a drop in the CBR index—decreasing from 50% to 20% for modified energy and from 25% to 17% for standard energy due to the dissipation of matric suction—the material maintains a stable S4 bearing class. Despite an initial classification often deemed “mediocre,” this soil exhibits sufficient immediate bearing capacity and low swelling potential (G