<![CDATA[The addition of a mixture consisting of native soil with 5 percent bamboo leaf ash and 5 percent cement has been shown to improve the California Bearing Ratio (CBR) and the strength of subgrade soil; however, its effect on rigid concrete slab deflection has not yet been explored. This study aims to analyze the influence of soil mixtures containing bamboo leaf ash and cement on rigid pavement deflection values using the finite element method through ETABS 21 software, with variations in CBR values, slab thickness, and central loading positions. The CBR data were obtained from previous studies, where the CBR value of untreated soil was 8,94 percent, while the CBR values of soil mixed with bamboo leaf ash and cement were 14,89 percent, 18.41 percent, 31.84 percent, and 41.43 percent. These CBR values were then converted into the modulus of subgrade reaction (k) using an empirical CBR–k equation. Subsequently, the rigid pavement was modeled in ETABS 21 and subjected to concentrated loads according to Class I road specifications (MST) at the center loading position in the longitudinal direction, transverse direction, and maximum deflection condition, with rigid pavement slab thickness variations of 265 mm, 275 mm, 285 mm, 295 mm, and 305 mm. The analysis results indicate that increasing the CBR value through the addition of bamboo leaf ash and cement, along with increasing the concrete slab thickness, consistently reduced rigid pavement deflection. At a CBR value of 8,94 percent with a slab thickness of 265 mm, the longitudinal deflection was recorded at -0,172 mm, whereas at a CBR value of 41,43 percent with a slab thickness of 305 mm, the deflection decreased to -0,089 mm. Similar reduction patterns were also observed in transverse deflection and maximum deflection values. The contribution of this study lies in demonstrating the effectiveness of bamboo leaf ash and cement as subgrade stabilization materials in enhancing subgrade stiffness and reducing rigid pavement deformation. The implication is that the use of these local materials has the potential to become a more efficient and sustainable alternative for subgrade improvement in rigid pavement design.]]>
