Microstructural and Mechanical Characterization of Compressed Earth Bricks Using Termite Mound Soil and Hydrated Lime as Sustainable Stabilizers

Compressed stabilized earth bricks (CSEBs) were produced by partially replacing natural lateritic soil with termite mound soil (TMS) at 15%, 20%, 25%, and 30%, while maintaining hydrated lime at 5%. Seven mixes were prepared: the control (100% soil), 100% TMS, 95% soil + 5% lime, and Mix formulation (M1) to Mix formulation (M4) containing 15%–30% TMS + 5% lime. The specimens were compacted and cured for 7, 14, and 28 days. Mechanical (compressive and flexural strength) and physical (density and drying shrinkage) properties were measured, while microstructural and chemical characteristics were assessed using XRF, XRD, FTIR, and SEM/EDS analyses. Compressive strength increased with both TMS content and curing age, peaking at 2.51 ± 0.083 MPa for 25% TMS after 28 days of curing. ANOVA revealed significant effects of curing age, TMS content, and their interaction ( p < 0.0001). Flexural strength followed a similar trend, showing strong cubic correlations ( R 2 = 0.91–0.96). After 28 days of curing, densities ranged from 1.59 to 1.71 g/cm 3 , and all mixes remained below the 0.25% drying shrinkage threshold. Microstructural and FTIR evidence indicated the formation of lime–clay pozzolanic products and complementary hydrated lime–TMS reactivity. The optimum performance occurred at 25% TMS + 5% lime, meeting or exceeding several national and international standards for CSEBs, indicating suitability for non–load‐bearing applications. These results demonstrate that TMS and lime can serve as locally available, low‐carbon stabilizers for producing durable compressed earth bricks.