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Przeglądaj Artykuły naukowe (WBiIŚ) wg Autor "Faculty of Applied Sciences, Collegium Mazovia Innovative School, 08-110 Siedlce, Poland"
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Pozycja Open Access Rheological, Mechanical, Microstructural and Radiation Shielding Properties of Cement Pastes Containing Magnetite (Fe3O4) Nanoparticles(Springer Nature, 2023-01) Sikora, Pawel; El-Khayatt, Ahmed M.; Saudi, H.A.; Liard, Maxime; Lootens, Didier; Chung, Sang-Yeop; Woliński, Paweł; Abd Elrahman, Mohamed; Faculty of Civil and Environmental Engineering, West Pomeranian University of Technology in Szczecin, Poland; Department of Physics, College of Science, Imam Mohammad Ibn Saud Islamic University, (IMSIU), Riyadh, Saudi Arabia; Department of Physics, Faculty of Science, Al-Azhar University, Women Branch, Nasr City, Cairo, Egypt; Sika AG, Switzerland; Department of Civil and Environmental Engineering, Sejong University, Seoul 05006, Republic of Korea; Faculty of Applied Sciences, Collegium Mazovia Innovative School, 08-110 Siedlce, Poland; Structural Engineering Department, Mansoura University, Mansoura City 35516, EgyptThis work examines the influence of iron oxide nanoparticles (Fe3O4 NPs) on neutron and gamma-ray radiation shielding characteristics of Portland cement paste. Experimental evaluations were supplemented with theoretical studies using NXCom program. Portland cement pastes with 5, 10, 15, 20, and 30 wt% of nanomagnetite cement replacement were produced. Moreover, rheological, early strength development, compressive strength, and mercury intrusion porosimetry (MIP) tests were performed. The results showed that increasing the amount of Fe3O4 NPs in a mix leads to a gradual increment in measured viscosity and yield stress. High nano-Fe3O4 content substantially impeded the early strength development process and led to a decrement in the 7- and 28-day compressive strength of cement paste. The MIP studies exhibited a gradual increment in total porosity, and average pore volume, as nano-Fe3O4 content was increased. All the macroscopic cross-sections of slow, fast and thermal neutrons constantly increased as a result of the addition of magnetite nanoparticles, with their variations being markedly linear. Similarly, gamma attenuation test results indicated that the addition of Fe3O4 powder enhances the shielding capability of paste in the energy range of interest (0.08–2.614 MeV). In conclusion, Fe3O4 nanoparticles can be successfully used in producing lead-free cementitious composites with improved gamma-ray and neutron shielding properties. However, certain drawbacks related to an increment in matrix porosity and thus a decrement in mechanical performance should be taken into account.Pozycja Open Access A systematic experimental study on biochar-cementitious composites: Towards carbon sequestration(Elsevier BV, 2022-05-26) Sikora, Paweł; Woliński, Paweł; Chougan, Mehdi; Madraszewski, Szymon; Węgrzyński, Wojciech; Papis, Bartłomiej K.; Federowicz, Karol; Ghaffar, Seyed Hamidreza; Stephan, Dietmar; Department of Civil Engineering, Technische Universität Berlin, Berlin 13355, Germany; Faculty of Civil and Environmental Engineering, West Pomeranian University of Technology in Szczecin, 70-311 Szczecin, Poland; Faculty of Applied Sciences, Collegium Mazovia Innovative School, 08-110 Siedlce, Poland; Department of Civil and Environmental Engineering, Brunel University London, Uxbridge UB8 3PH, UK; Building Research Institute (ITB), 00-611 Warsaw, PolandThe utilisation of biochar, the carbon negative product of pyrolysis, reduces the carbon footprint of the cementitious composites as it possesses the potential to replace the consumption of Portland cement. In a systematic investigation, biochar was used as a partial cement replacement for up to 20 wt% in both cement pastes and mortars. A comprehensive experimental framework was conducted to evaluate the impact of biochar replacement on the performance of (i) cement paste in terms of hydration kinetics, rheology, strength development, porosity, and (ii) mortars in terms of mechanical, thermal, and transport properties. In addition, the durability of developed mortars, including freezing and thawing resistance, thermal resistance, acid (corrosion) resistance, flammability, and smoke production, were examined. The results revealed that lower replacement rates of cement with biochar (up to 5 wt%) do not substantially change the performance of cementitious composites. However, incorporating biochar in higher dosages (i.e., 20 wt%) influenced the hydration process, reduced flexural and compressive strengths by 49% and 29%, respectively, and increased the water absorption coefficient by 60% compared to control specimens. The same cement mortar demonstrated the most promising freeze-thaw (i.e., 98% relative residual compressive strength), acid resistance as well as considerably lower thermal conductivity. In addition, regardless of biochar content, mortars did not exhibit flammability. Therefore, this study demonstrated that despite specific technical issues, biochar can be successfully incorporated into high dosage to cementitious composite as an alternative binder with minimum environmental impacts to improve durability and insulating performance of mortars.