Comparative Study of Natural and Artificially Stabilized Soils

Calcareous marl soil, prevalent in the Eastern Province of Saudi Arabia, is widely utilized in construction but poses challenges due to its water sensitivity, variable engineering behavior, and insufficient stability. This study investigates sustainable stabilization methods using recycled crushed glass (RCG) and palm fiber (PF) to enhance compaction characteristics, addressing both environmental concerns and infrastructure reliability. Through systematic Standard Proctor tests, the effects of varying RCG (0%, 5%, 10%, 15%, & 20%) and PF (0.5%, 1.0%, 1.5%, & 2%) dosages on maximum dry density (MDD) and optimum moisture content (OMC) of calcareous marl soil were evaluated. Results demonstrated that 5% RCG optimized MDD at 2.027 g/cm³ (vs. 2.013 g/cm³ for untreated marl soil), with OMC slightly reduced to 10.021% (vs. 10.796% for untreated marl soil), attributed to improved particle packing and reduced water demand. Higher RCG percentages (>5%) diminished MDD due to lightweight granular dominance. Conversely, 1.5% PF achieved the peak MDD of 2.020 g/cm³ and significantly lowered OMC to 7.16%, leveraging fiber’s bridging effect and hydrophobic properties. Both the lower (<1.5%) and excessive PF contents (>1.5%) disrupted soil structure, reducing density. The findings highlight critical thresholds for both additives: RCG enhances compaction marginally but requires controlled incorporation, while PF substantially reduces moisture dependency, optimizing MDD and soil-water interactions. This research underscores the viability of RCG and PF as eco-friendly stabilizers, offering cost-effective solutions for marl soil improvement in road bases, embankments, and foundations. By repurposing waste materials, the study advances sustainable construction practices, balancing engineering performance with environmental stewardship.