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

Data Availability Statement: The datasets generated and/or analyzed during this study are available from the corresponding author upon reasonable request.Copyright © 2023 by the authors. Incorporating metal oxide nanoparticles into cement-based composites delays the hydration process and strength gain of cementitious composites. This study presents an approach toward improving the performance of bismuth oxide (Bi2O3) and gadolinium oxide (Gd2O3) particles in cementitious systems by synthesizing core–shell structures via a sol-gel process. Two types of silica coatings on cementitious pastes with 5% and 10% substitution levels were proposed. The rheology, hydration, and mechanical properties of the pastes were analyzed to determine the relationship between the coating type and nanoparticle concentration. The results indicate that despite the significant disparities in the performance of the resulting material, both methods are appropriate for cement technology applications. Bi2O3’s silica coatings accelerate the hydration process, leading to early strength development in the cement paste. However, due to the coarse particle size of Gd2O3, silica coatings exhibited negligible effects on the early age characteristics of cement pastes.National Science Centre, Poland (project no. 2020/39/D/ST8/00975 (SONATA-16))

Functional Bi2O3/Gd2O3 Silica-Coated Structures for Improvement of Early Age and Radiation Shielding Performance of Cement Pastes

Data Availability Statement: The datasets generated during and/or analyzed during the current study are available from the corresponding author upon reasonable request.Copyright © 2024 by the authors. This study presents a new approach towards the production of sol-gel silica-coated Bi2O3/Gd2O3 cement additives towards the improvement of early mechanical performance and radiation attenuation. Two types of silica coatings, which varied in synthesis method and morphology, were used to coat Bi2O3/Gd2O3 structures and evaluated as a cement filler in Portland cement pastes. Isothermal calorimetry studies and early strength evaluations confirmed that both proposed coating types can overcome retarded cement hydration process, attributed to Bi2O3 presence, resulting in improved one day compressive strength by 300% and 251% (depending on coating method) when compared to paste containing pristine Bi2O3 and Gd2O3 particles. Moreover, depending on the type of chosen coating type, various rheological performances of cement pastes can be achieved. Thanks to the proposed combination of materials, both gamma-rays and slow neutron attenuation in cement pastes can be simultaneously improved. The introduction of silica coating resulted in an increment of the gamma-ray and neutron shielding thanks to the increased probability of radiation interaction. Along with the positive early age effects of the synthesized structures, the 28 day mechanical performance of cement pastes was not suppressed, and was found to be comparable to that of the control specimen. As an outcome, silica-coated structures can be successfully used in radiation-shielding cement-based composites, e.g. with demanding early age performances.National Science Centre of Poland within Project no. 2020/39/D/ST8/00975 (SONATA-16)

Recycled brick aggregates in one-part alkali-activated materials: Impact on 3D printing performance and material properties

Data availability: Data will be made available on request.This study investigates the printability of one-part brick powder-based alkali-activated materials (AAMs) containing end-of-life brick particles as aggregate. The novel formulation showcases promise for 3D printing of small to medium-sized building blocks, reminiscent of a Lego-type system, capitalising on the rapid setting time inherent to one-part AAMs. The effect of replacing up to 50% by weight of natural aggregate with brick aggregate on the fresh properties of brick powder-based alkali-activated materials, including slump measurements, flowability, setting time, open time and green strength were investigated. In addition, the flexural and compressive strength of the 3D printed mixtures were determined and compared to those of cast specimens. The buildability and microstructure were also examined. The results showed that incorporating high porous and rough brick aggregate to replace natural aggregate is beneficial in improving the mixtures’ slump, which is essential for retaining the shape of the printed layers. However, it decreased the flowability, setting time and open time when incorporating up to 50% brick aggregate. The green, flexural and compressive strengths were increased with increasing brick aggregate content up to 50% due to enhancing interlock between the binder and brick aggregate, and the better compaction because of the absorption properties of brick aggregate. The mechanical results revealed the better performance of 3D printed specimens than the cast specimens. Moreover, the incorporation of brick aggregate enhanced the buildability of the mixtures showcasing their potential in advancing 3D printing capabilities.This work was funded as part of the DigiMat project, which has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement ID: 101029471. This research was funded in part by the National Center for Research and Development (NCBR), Poland within Project no. ERA-MIN3/140/Recycl3D/2022 (ERA-NET Cofund ERA-MIN3 (Joint Call 2021)). The funding provided by FCT - the Portuguese Foundation for Science and Technology, is acknowledged: references UIDB/04625/2020 (CERIS research centre) and ERA-MIN3/0001/2021 (ERA-NET Cofund ERA-MIN3)

Elements of equipment for road surfaces with photoluminescence marking

W przestrzeni publicznej stosuje się wiele oznaczeń służących polepszeniu bezpieczeństwa. Wspomniane oznaczenia bazują na komunikacji wizualnej, często są podświetlane. Takie rozwiązania wymagają doprowadzenia instalacji elektrycznej. Interesującym rozwiązaniem eliminującym zastosowanie kosztownej energii elektrycznej jest zastosowanie pigmentów fotoluminescencyjnych zespolonych z elementami nawierzchni drogowej. Artykuł przedstawia ocenę właściwości technicznych i użytkowych elementów wyposażenia nawierzchni drogowej z oznakowaniem fotoluminescencyjnym.In the public space, one can encounter many markings which serve to improve safety. These markings are based on visual communication and they often tend to be illuminated. Such solutions require an electrical installation. An interesting solution eliminating the use of costly electricity is the use of photoluminescent pigments combined with the elements of the road surface. The article presents the assessment of technical and functional properties of elements of road surface equipment with photoluminescent marking

Development of 3D printed heavyweight concrete (3DPHWC) containing magnetite aggregate

Data availability: Data will be made available on request.The main objective of this study is to develop 3D printed heavyweight concrete (3DPHWC) to produce elements with a dry density of up to 3500 kg/m3 by replacing natural aggregate (SA) with magnetite aggregate (MA) up to 100%. A comprehensive systematic study was conducted to thoroughly assess mixtures' mechanical properties, physical proficiency, fresh properties, and printing qualities. The inclusion of MA exhibited the desired fresh properties required for 3D printing and promising physical and mechanical properties. Evaluation of the mechanical properties of designed 3DPHWC indicates that replacing SA with MA increases both cast and printed samples' strengths. The 3D printed M100 sample achieved higher 28 days flexural and compressive strengths by 18 % and 20 %, respectively, compared to printed control mix (M0). Micro-CT study correspondingly demonstrated improvements in the composites' porosity, pore size, and pore morphologies. The linear attenuation coefficients (LACs) and half-value layer (HVLs) for slow neutron and gamma-ray were measured to assess radiation shielding characteristics. A significant performance improvement was obtained for slow neutrons by introducing the magnetite aggregate. Unlike slow neutrons, no significant difference was observed between cast and printed samples against γ-rays. Moreover, the effect of porosity on the shielding performance was discussed.This research was funded in whole by the National Science Centre, Poland within Project No. 2020/39/D/ST8/00975 (SONATA-16). This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (Ministry of Science and ICT Grant no. NRF-2021R1A4A3030924)

Development of 3D printed heavyweight concrete (3DPHWC) containing magnetite aggregate

The main objective of this study is to develop 3D printed heavyweight concrete (3DPHWC) to produce elements with a dry density of up to 3500 kg/m3 by replacing natural aggregate (SA) with magnetite aggregate (MA) up to 100%. A comprehensive systematic study was conducted to thoroughly assess mixtures' mechanical properties, physical proficiency, fresh properties, and printing qualities. The inclusion of MA exhibited the desired fresh properties required for 3D printing and promising physical and mechanical properties. Evaluation of the mechanical properties of designed 3DPHWC indicates that replacing SA with MA increases both cast and printed samples' strengths. The 3D printed M100 sample achieved higher 28 days flexural and compressive strengths by 18 % and 20 %, respectively, compared to printed control mix (M0). Micro-CT study correspondingly demonstrated improvements in the composites' porosity, pore size, and pore morphologies. The linear attenuation coefficients (LACs) and half-value layer (HVLs) for slow neutron and gamma-ray were measured to assess radiation shielding characteristics. A significant performance improvement was obtained for slow neutrons by introducing the magnetite aggregate. Unlike slow neutrons, no significant difference was observed between cast and printed samples against γ-rays. Moreover, the effect of porosity on the shielding performance was discussed