Synthesis and characterization determination of boric acid for gamma and neutron shielding efficiency of bio-caulk incorporated high-performance concrete (HPC)

Abstract

Boron is a naturally occurring element having the ability to react with a wide range of various elements to form different compounds. Boric acid (BA) compounds will have significant applications like radiation shielding. When boron compounds are added to concrete it increases the neutron attenuation and acts as a suppressor of secondary-capture gamma rays. The High-Performance Concrete (HPC) – M40 grade has been used in most reactor constructions due to its high attenuation properties. Nano boron produced by 20 h of ball milling was mixed with uniform distribution in the concrete. This pulverized nano boron was sampled every 4 h and characterized by XRD, FTIR and FE-SEM. The setting time was determined after adding 1, 2, 3, 4 & 5% (w/w) of milled and unmilled BA materials into the HPC-M40 concrete as a replacement for cement. A significant radiation attenuation effect was observed in the 5 cm thickness of the concrete which showed up to 80% reduction in gamma rays attenuation compared to the conventional concrete. The bio-caulk, a bacterial concrete, was used as a replacement for water to increase the setting time and strength properties. 10% of Bacillus sphaericus inoculum was used to synthesize bio-Caulk which has self-healing properties at the micro-level cracks. The bio-caulk borated HPC - M40 grade has better shielding properties at 5% of boron as an admixture. The BA composite incorporated bio-caulk concrete showed less setting time, high compressive strength and better radiation shielding properties.