Mechanical and radiation shielding properties of concrete containing commercial boron carbide powder

Boron-containing compounds have an excellent radiation shielding capability against slow neutrons. Moreover, sassolite in boron-containing compounds adversely affects cement hydration by retarding cement setting times. Accordingly, experimental and analytical investigations were carried out to examine the filler effect of commercial boron carbide (B4C) fine powder with a mean particle diameter of 2.64 μm on Portland cement hydration reaction, and concrete mechanical and radiation shielding properties. Isothermal calorimetry method was used to study the heat evolution and the cement degree of hydration of mixes containing 0, 25, 50 and 75% of B4C to cement by weight. Effects of adding B4C on concrete compressive strength were then investigated. Analytical investigations, specifically mass attenuation coefficient using WinXcom program and effective atomic number using Auto-Zeff, were carried out to evaluate the radiation shielding of corresponding concrete mixes for photon energies ranging from 10 keV to 10 MeV. Moreover, macroscopic effective removal cross-sections for fast neutrons and thermal neutron macroscopic absorption cross-sections were calculated using MRCsC program and JANIS-4 software, respectively. The results confirm that the presence of sassolite in the studied B4C powder retards the hydration reaction for the first 24 h and reveal significant improvements in concrete strength thereafter with the increase of boron carbide due to the filler effect. Furthermore, the addition of boron carbide yielded measurable improvement in neutron shielding capabilities of concrete mixes.