Design of bismuth oxide nanoparticles as lightweight aggregate in cement composites against X‐rays

Abstract

Nowadays, heavy concrete is becoming one of the most commonly used materials against X‐ray radiation (medical or nuclear). This type of concrete is enriched by heavy aggregates with high density and/or high atomic number such as magnetite or barite, which allow to obtain an appreciable shielding effect but may present problems related to high manufacturing costs. Moreover, very heavy concretes can be achieved with iron or lead shot as aggregate, but in this case, the big problem is related to the toxicity and harmful for human health. In this research work, bismuth—a cheap, nontoxic, and biocompatible element, characterized by having a high atomic number Z (Z = 83)—has been used as additive in cement mixture, with the purpose to indagate its effectiveness as shielding agent and to analyze the mechanical strength response.

Enhancing the Fresh and Early Age Performances of Portland Cement Pastes via Sol-Gel Silica Coating of Metal Oxides (Bi2O3 and Gd2O3)

“…In recent years, there has been growing concern regarding the production of lead-free materials; thus, various additives have been used, including Bi 2 O 3 , Ti 2 O 3 , WO 3 , Gd 2 O 3 , and Fe 3 O 4 . Particular interest is placed on the application of Bi 2 O 3 due to its high atomic number (Z = 83), low price, nontoxicity, and biocompatibility [5].…”

“…The lower mechanical performance and slower strength development of cement-based composites containing nano-Bi 2 O 3 is mainly attributed to its high-volume replacement rate with cement. To ensure proper radiation shielding characteristics, the addition of micro-or nanoparticles usually exceeds >5 wt% of binder [5,[9][10][11][15][16][17][18]. In contrast, the State-of-the-Art recommended dosages of nanoparticles in cementitious systems, toward improving durability and mechanical characteristics, should usually not exceed 5 wt% of binder [19,20].…”