PSI - Issue 73

Loran Nermend et al. / Procedia Structural Integrity 73 (2025) 130–137 Author name / Structural Integrity Procedia 00 (2025) 000–000

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Keywords: 3d printed concrete; nanoparticles; fire resistance; elevated temperature; electrical resistivity

1. Introduction 3D printed concrete (3DPC) technology has attracted significant attention due to its ability to enhance traditional concrete construction methods. It enables the development of more advanced, topology-optimized structures. To date, 3DPC has been applied in various civil engineering projects, including urban architectural elements, residential buildings, and bridges. However, its potential extends further, showing strong potential for more demanding applications such as the construction of shelters and protective walls. As presented by Du et al. (2025), 3D printed concrete (3DPC) can be utilized in the production of ballistic-resistant barriers. In recent years, the technology of additively manufactured polymer-based radiation and electromagnetic shielding components has been studied by several research teams, including Juračka et al. (2023) and Cao et al. (2024). These studies highlight the strong potential of this technology in applications such as space engineering and lunar missions. The ability to optimize topologies and improve the geometric freedom opens up vast possibilities for developing advanced radiation shielding barriers. The effectiveness of concrete in attenuating neutron and ionizing radiation can be significantly enhanced by incorporating specific types of aggregates or adding heavyweight fillers. Therefore, combining proper topology optimization with tailored material composition can substantially improve the shielding performance of the final barrier. Advancing this technology is of great importance, as concrete remains one of the most widely used materials for constructing biological shields to protect humans from radiation. Currently, limited research on the production of 3D printed concrete (3DPC) for radiation shielding is available in the literature. For instance, the potential of 3DPC was explored by Le Pape et al. (2020). Moreover, Federowicz et al. (2023) proposed the use of magnetite aggregate to produce heavyweight 3DPC. In another study, Sikora et al. (2025) suggested enhancing radiation attenuation properties by incorporating nanosized particles—specifically bismuth oxide (Bi 2 O 3 ) and gadolinium oxide (Gd 2 O 3 )—as partial cement replacements. The improved shielding performance was attributed to the inclusion of high atomic number (Z) elements (Bi 2 O 3 and Gd 2 O 3 ), as well as the high neutron capture cross-section of Gd 2 O 3 . However, the inclusion of fine particles in cementitious systems can lead to certain drawbacks, such as delayed hydration and consequently reduced early strength development. To address these issues, Sikora et al. (2025) proposed coating the particles with reactive silica to mitigate the aforementioned effects. Additionally, the presence of nanosilica can positively influence the rheological properties of 3DPC. Based on previous research, a mixture containing 2.5 vol% of bismuth oxide and gadolinium oxide was found to be suitable for use in 3DPC. This study aims to evaluate the suitability of both pristine (uncoated) and silica-coated admixtures in terms of their impact on the durability of 3DPC. Specifically, it investigates whether the inclusion of a small dosage of radiation shielding admixtures adversely affects the electrical resistivity and thermal resistance of the material. 2. Materials and Methods 2.1. Materials A 3D printable cementitious composite was produced using ordinary Portland cement CEM I 42.5R (CEMEX, Poland), silica fume (Mikrosilika Trade Company), and fly ash obtained from ImmerBau (Poland). As an aggregate, natural river sand obtained from SKSM, Poland, was used with a maximum particle size of ≤ 2 mm. In all mixes, a fixed amount of Sika ViscoCrete 111 (SP) superplasticizer was used. Particle size distribution of used materials is presented in Figure 1.