66. Oyeleke O.I. (2009). Half value layer (HVL) of different Mixtures of Cement, Sand, and Gravel for γ-rays from Co-60. Journal of science, education and technology, 2(1). 197-202.

Abstract

Concrete can be obtained using different mixture proportion of sand, gravel and cement depending on the structural strength desired (purpose). This work attempts to investigate the radiation shielding capacity of different concrete mixtures for gamma energies of Cobalt-60 source. Three standard common mixing proportion of concrete samples widely used in Nigeria were prepared (with cement, sand, and gravel ratios of 1:1.5:3; 1:2:4; and 1:3:6) and labeled A, B, and C respectively. The linear attenuation coefficients ( μ, cm-1) of mixtures sample was determined for cobalt-60 source using a well type NaI(Tl) detector and a spectrum analyzing software (Genie 2000), and consequently their half value layers (HVL) were calculated as well. Sample A was found to have a half value layer of 8.56 cm and 11.18 cm; B had HVL of 15.40 cm and 22.35 cm; and C has a HVL of 11.95cm and 15.40 cm for gamma energies of 1.17 MeV and 1.33 MeV respectively. From the results sample A is a better attenuator of gamma rays than the other two samples at the same gamma energy and sample thickness. This concrete mixture can then be said to be the best for radiation shielding amongst the three commonly used in Nigeria.