Evaluation of the effects of bismuth oxide (Bi2O3) micro and nanoparticles on the mechanical, microstructural and γ-ray/neutron shielding properties of Portland cement pastes. (17th May 2021)

• Record Type: Journal Article
• Authors: Sikora, Pawel; El-Khayatt, Ahmed M.; Saudi, H.A.; Chung, Sang-Yeop; Stephan, Dietmar; Abd Elrahman, Mohamed
• Is Part Of: Construction & building materials. Volume 284(2021)
• Publication Date: 2021-05-17
• Subjects: Cement-based composites -- Gamma-ray shielding -- Neutron shielding -- Bismuth oxide -- Nanoparticles; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.122758
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: The effects of micro-Bi2 O3 and nano-Bi2 O3 powders were compared. Incorporation of high dosage of nano-Bi2 O3 results in lower strength loss when compared to micro-Bi2 O3. Addition of both Bi2 O3 powders enhances the gamma-ray shielding capability of pastes. Addition of nano-Bi2 O3 improved the slow neutron attenuation ability of cement pastes. Both Bi2 O3 powders are effective in producing lead-free cementitious composites with improved shielding properties. Abstract: This study presents a comparison of the effects of micro-Bi2 O3 and nano-Bi2 O3 powders on the mechanical, microstructural and gamma / neutron shielding properties of Portland cement pastes. Cement pastes with various ratios of cement (up to 30 wt-%) replaced with Bi2 O3 micro and nanoparticles were prepared. Consistency, compressive strength, water accessible porosity and mercury intrusion porosimetry tests were performed, in order to characterize their engineering properties. In addition, experimental and theoretical evaluations of γ-ray and neutron shielding properties were performed. The results showed that the incorporation of Bi2 O3 powders gradually leads to a decline in cement pastes' compressive strength and an increase in their porosity, as the amount of powder is increased. However, the deterioration rate varies depending of type of powder used, in favor of nano-Bi2 O3 . Gamma attenuation tests results indicate that the addition of Bi2 O3 powders enhances the shielding capability of pastes, in the energy range of interest (0.08–2.614 MeV). However, the effects of particle size on γ-ray attenuation are negligible in that energy range. Slow neutron attenuation study showed that the addition of nano-Bi2 O3 improved the shielding ability of cement pastes, with enhancements ranging between 15.3% and 25.5% for samples with 5 and 30 wt-% nano-Bi2 O3, respectively. In conclusion, this study shows that the addition of nano or micro-Bi2 O3 is effective in producing lead-free cementitious composites with improved γ-ray and neutron shielding properties. Unlike gamma shielding, nano-sized Bi2 O3 has a better ability to attenuate neutrons, in comparison to their micro-sized counterparts.