## 3 Materials, Methods, and Equipment  
### Granulometric and Index Properties Analysis of Well-Graded Sand  
This study utilized uniformly graded sand from the Wudil River in Kano State, Nigeria. The sand was washed, oven-dried, and sieved between 2 mm and 0.075 mm openings. Particle size distribution was determined using ASTM D422-63, specific gravity was determined using ASTM D854-23, and relative density was determined using ASTM D4254-23. The material was classified as well-graded sand (SW) according to USCS (ASTM D2487). Figure 2 depicts the grain size distribution curve, while Table 2 summarizes physical properties including void ratios, specific gravity, and uniformity coefficients. This thorough characterization ensures reliable experimental results when investigating sand-pile material interface behavior. The geotechnical properties in the table characterize the sand material comprehensively. The particle size distribution (D\({}_{10}\) = 0.10 mm, D\({}_{30}\) = 0.30 mm, D\({}_{50}\) = 0.60 mm, D\({}_{60}\) = 0.80 mm), coefficient of curvature (C\({}_{\rm{c}}\) = 1.13), and coefficient of uniformity (C\({}_{\rm{u}}\) = 8.0) classify this material as well-graded sand (SW) using USCS. The grain size range (0.01-2.0 mm) confirms the pure sand composition without significant silt or gravel. With a specific gravity of 2.68, void ratio limits of 0.453-0.920, and a dry unit weight range of 13.7-18.2 kN/m\({}^{3}\), the material demonstrates typical quartz sand characteristics. The optimum moisture content (7-10%) indicates good workability and predictable com \begin{table}
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**Author (Study)** & **Year** & **Methods** & **Results Summary** \\ \hline Performance of hybrid cross-laminated timber (CLT)–concrete composite by [PERSON], [PERSON] [21] & 2023 & Push-out tests & CLT–concrete composites exhibit efficient force-slip response and slip modulus, with defined failure modes. \\ \hline Steel–concrete composites with anti-pullout connectors by [PERSON], [PERSON] [22] & 2023 & Sample analysis & Anti-pullout connectors reduce rebar stress by \textgreater{}50\% and mitigate the capacity decline. \\ \hline Composite timber columns confined with steel by [PERSON] and [PERSON] [23] & 2021 & Compression experiments & Confined timber columns show enhanced compressive performance. \\ \hline Timber–concrete composites (TCC) by [PERSON] and [PERSON] [11] & 2024 & Case studies, regulatory analysis & TCC systems reduce embodied carbon by 30\% and increase timber used in construction. \\ \hline Steel–concrete joints in hybrid bridges by [PERSON], [PERSON] [24] & 2025 & Analytical investigation & Load transfer mechanisms in steel–concrete joints depend on connection design and material synergy. \\ \hline Steel, aluminum, and composite structures by [PERSON], [PERSON] [25] & 2024 & Review of trends & Covers advancements in composite structural systems and design frameworks. \\ \hline Composite fender piles by [PERSON], [PERSON] [26] & 2024 & Bending tests & Bending energy absorption varies with pile material and configuration. \\ \hline Steel–timber hybrid buildings by [PERSON] and [PERSON] [12] & 2025 & LCA analysis & Life cycle assessments (LCAs) reveal that timber–concrete hybrids reduce embodied carbon \\ \hline Current Study & 2025 & Classical bearing capacity methods (e.g., Terzaghi, Vesic) + PLAXIS 3D simulations & Work on composite systems, soil densification, and sustainability, offering optimized design strategies for semi-arid regions with fluctuating groundwater. \\ \hline \end{tabular}
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Table 1: Literature review. paction behavior. These properties provide essential parameters for numerical modeling and geotechnical applications, including backfill, foundation support, and drainage layers.