Physical, mechanical, and radiation attenuation properties of serpentine concrete containing boric acid

Serpentine and boric acid are effective materials to produce the radiation-shielding concrete (RSC) for attenuating the fast and thermal neutrons, respectively. Therefore, this study investigates the effect of boric acid (0, 1, and 3% by cement weight) on the physical, mechanical, microstructural, and radiation shielding properties of serpentine concrete. The results showed that the addition of boric acid hindered the hydration of cement through the generation of amorphous borate material, which encapsulates the cement phases and retards their transformation into hydration products. Such a retardation process negatively influenced the mechanical properties of boric acid-bearing concrete and contributed to the thicker and less condensed interfacial transition zone. Furthermore, unlike total γ-rays, boric acid enhanced the attenuation properties of serpentine concrete against thermal and fast neutrons favoring the former. There was a satisfying agreement between the theoretical and measured values of fast neutron attenuation parameters. However, negligible variations in the theoretical values of photon interaction parameters showed that porosity was the principal reason for the reduction in gamma-ray attenuation as a result of boric acid addition.