In Awka and most parts of Anambra State, plastering is commonly carried out using the cheapest and nearest available materials like river-bed sand dredged from the Onitsha reach of the River Niger or clayey borrow-pit soils excavated locally, which are often mixed by eye, leading to frequent cracking, blistering, delamination, poor bonding, and patchy finishes. This study therefore characterized the geotechnical, physico-chemical, and mineralogical properties of borrow-pit soils from Amansea and Ebenebe, river-bed sand from Onitsha, and four laboratory-prepared blends at 80/20 and 60/40 (sand/soil) ratios using particle-size analysis, Atterberg limits, specific gravity, Standard Proctor compaction, X-ray fluorescence (XRF), and X-ray diffraction (XRD). Results showed that all materials are highly siliceous (SiO₂ 77–87 wt.%) and quartz-dominated (86–96 wt.%) with very low fines content (< 0.6 %), making them essentially non-plastic despite the clayey appearance of the borrow-pit soils (kaolinite only 3–7 wt.%). Blending Onitsha river-bed sand with borrow-pit soils significantly reduced fines, water demand, and plasticity while increasing maximum dry density and specific gravity. The 60 % Onitsha + 40 % Amansea blend exhibited the optimum combination: highest maximum dry density (1.86 Mg/m³), low optimum moisture content (11 %), very low fines (0.39 %), and the cleanest oxide profile, clearly outperforming the individual raw materials. The widespread plaster defects observed locally are thus attributable to the use of unblended or poorly proportioned materials, while a simple, controlled 60:40 blend offers a strong, shrinkage-resistant, and sustainable plastering aggregate using only locally available resources.