Mechanical Characterization of a Composite Mortar Made from Lateritic Soils Stabilized with Autogenous Welding Lime and Reinforced with Palm Kernel Cake (PKC) for the Production of Compressed Earth Bricks (CEBs)
Sustainable construction in sub-Saharan Africa is confronted with a dual requirement: meeting a high demand for housing while reducing the carbon footprint of the building sector. In this context, this study investigates the mechanical performance of a composite mortar based on local resources, combining four lateritic soils from Benin, lime derived from autogenous welding (an artisanal by-product), and palm kernel cake (PKC) fibers, an agricultural waste. The experimental program, structured in two phases, is based on lateritic soils from Zogbodomey, Dassa-Zoumè, Glazoué, and N’Dali, representative of the pedological variability of Benin, with complementary X-ray diffraction (XRD) analyses used to establish relationships between mineralogy and performance. The first phase assesses the influence of lime content (0% to 30%) on compressive strength at 7, 14, and 28 days, as well as flexural strength at 28 days, while the second phase introduces PKC contents (0.25% to 2%) into the optimal formulation. The results show that a 20% lime content is optimal, with 28-day compressive strengths ranging from 4.58 to 5.51 MPa. The lime exhibits a high portlandite content (85.4%), ensuring strong reactivity, while the N’Dali soil is characterized by the presence of kaolinite (26%). The incorporation of 1% PKC improves compressive strength (up to 8.5%) and, more significantly, flexural strength (up to 66%), indicating pseudo-ductile behavior associated with crack-bridging mechanisms. The optimal formulations exceed the 4 MPa threshold required for load-bearing masonry and exhibit performance comparable to a reference cement mortar, thereby opening promising prospects to produce sustainable compressed earth blocks in Benin, within a circular economy framework and a strategy aimed at reducing CO2 emissions.
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