Evaluation of Radiation Shielding Properties of Clay-Barite Composite Blocks for Medical Facilities

The construction of radiation shielding in diagnostic imaging rooms, radiotherapy bunkers, and nuclear medicine hot laboratories requires materials with high density and adequate gamma attenuation. Commercially imported lead and barite concrete are expensive in the Nigerian construction market. This study evaluates the radiation shielding properties of clay-barite composite blocks fabricated using locally available barite ore from Taraba State and clay from Benue State. Blocks are prepared with barite-to-clay mass ratios of 1:1, 2:1, and 3:1 at standard block dimensions. Density, compressive strength, and linear attenuation coefficients for Cs-137 gamma rays (662 keV) and Co-60 gamma rays (1.25 MeV average) are measured. Attenuation coefficients are determined using the narrow beam transmission method with an NaI(Tl) scintillation detector. Results indicate block densities of 1,940 to 2,480 kg per cubic metre, increasing with barite content. Half-value layer for Cs-137 decreases from 65 mm at 1:1 ratio to 41 mm at 3:1 ratio, compared to 63 mm for standard concrete. The 3:1 composite achieves compressive strength of 12.4 MPa, adequate for non-load-bearing wall applications. The study provides design data for cost-effective radiation shielding construction in Nigerian healthcare facilities. Keywords: radiation shielding, clay-barite composite, gamma attenuation, medical facility, barite