Heat effect on the shielding and strength properties of some local concretes

The effect of heat on strength and on γ-ray and neutron shielding properties of four types of the local concretes (denoted as H-mix, F-mix, D-mix and S-mix) were investigated, the samples were exposed to temperatures between 20 and 800 °C.Small losses in attenuation coefficients for γ-rays and neutrons were observed for the studied types of concretes at 100 °C, while there were no changes in strength for H-mix and F-mix compared to 10–15% loss of strength (the ratio of decreased compressive strength after exposure to heat to the original one) in D-mix and S-mix. No significant loss in attenuation has been noticed between 100 and 400 °C while unexpected increases in strength in some samples have been observed. No changes between 400 and 500 °C in γ-rays attenuation except for D-mix which suffers a high loss in γ-rays attenuation. The neutron attenuation decreases for the studied types at these temperatures, while the strength increases except for D-mix.F-mix and D-mix lost their integrities (destroyed) between 500 and 550 °C and losses in attenuation and increase in strength for the other two types. S-mix concrete lost 50% of its strength at 550 °C, while H-mix concrete lost 50% of its strength at 650 °C.It can be concluded that the H-mix which contains hematite aggregates have the best attenuation coefficients for both γ-rays and neutrons and the best resistant for high temperatures effects.