Search

The availability of water and the type of interlayer anions present affect the arrangement and interlayer spacing of layered double hydroxide (LDH). A systematic study of the effect of relative humidity (RH) on the basal spacing of phosphate intercalated, magnesium aluminum LDHs (MgAl–PO4 LDH) was conducted, confirming that MgAl‐PO4 LDH exhibit distinct interlayer spacing corresponding to separate low‐ and high‐hydration states produced when exposed to low and high humidity conditions. The transition from the low‐ to high‐hydration form begins when RH exceeds 33% and is accompanied by the transition from one to two interlayers of water. An improved understanding of the effect of RH on MgAl–PO4 LDHs will enable more accurate atomistic modeling and experimental characterization of MgAl–PO4 LDHs and may lead to improvements in the tunability of MgAl‐PO4 LDHs for commercial applications such as slow‐release fertilizer. [ABSTRACT FROM AUTHOR]

Durability is crucial for reinforced concrete, directly influencing the service life of structures. The presence of aggressive agents, especially chloride ions, significantly impacts durability. This study investigates the differences between ASTM C1202 and IBRACON/NT Build 492 standards in concrete containing various types of cement designed for a characteristic compressive strength of 40 MPa. Forty-eight cylindrical samples were prepared using eight types of Portland cement, including those with blast furnace slag, filler, and pozzolanic materials. Chloride migration tests were performed according to the ASTM C1202/2022 and IBRACON/NT Build 492/1999 methodologies. At a 95% confidence level, the results indicated that concrete made with filler-containing cement (PCII F-SR and PC II F) showed the poorest chloride resistance, with charge passing values exceeding 4000 coulombs (ASTM C1202) and diffusion coefficients above 10 × 10−12 m2/s (IBRACON/NT Build 492). In contrast, concrete containing high slag cement (PC III-SR) and pozzolan cement (PC IV) demonstrated superior resistance to chloride penetration, with charge passing values below 1500 coulombs and diffusion coefficients under 5 × 10−12 m2/s. Notably, discrepancies in classification were observed, as PC II Z (fly-ash based) and PC II E-SR (slag-based) received different ratings under the two methods. ASTM C1202 was found to be more stringent than NT Build 492, highlighting significant variations in the classification criteria between these standards. Based on the findings, new interval values are proposed for classifying concrete regarding the risk of chloride ion penetration, particularly for the ASTM C1202 standard, in order to better align with performance-based durability criteria and improve classification accuracy. [ABSTRACT FROM AUTHOR]

Purpose: As the applications of nuclear technology increase in today’s world, radiation protection becomes even more important. Radiation protection is important in medical imaging applications and radiotherapy rooms. Therefore, in this research, we have investigated features of the ionizing radiation shielding of the modified cement composite with iron, strontium, zinc, and zirconium elements in the photon energy range of 15 keV to 10 MeV. Materials and Methods: To extract such features, it is necessary to use a computational method. In this research, we have done all our calculations based on the Geant4 tool based on the Monte Carlo method. This tool is a multipurpose tool that can be used for particle transport calculations such as electrons, protons, neutrons, heavy charged particles, and photons in different environments such as human tissues. Results: The mass attenuation coefficient of the samples was calculated using the Geant4 Monte Carlo simulation tool and compared with the results of the Phy-X program, which was in good agreement. To evaluate the radiation shielding capabilities, other quantities such as the linear attenuation coefficient, the thickness of the tenth value layer, the thermal neutron cross-section, absorption rate of thermal neutrons, and the cross-section of the fast neutron removal are determined. Conclusions: According to the quantitative results, cement composite is more effective in absorbing and weakening gamma and neutrons. Calculations of radiation shielding quantities show that cement composites containing tungsten carbide and thallium oxide waste powder are a suitable combination and a practical material for radiation control. In addition, by returning industrial waste to the production sector, they will also be effective in reducing environmental pollution. In general, the cement composite sample containing iron, thallium, zinc, zirconium, tungsten, and carbon elements shows a high potential for radiation protection applications. This study highlights the effective radiation shielding potential of cementitious composites and demonstrates the importance of advancing safety measures in medical and industrial radiation applications.

The mechanical performance of MoW‐HfN, a surrogate cermet for MoW‐UN Nuclear Thermal Propulsion (NTP) fuel, was characterized from room temperature to 1600°C. The modulus of elasticity and flexure strength were obtained from four‐point bend tests. Those tests revealed a loss of stiffness with increasing temperature and systematic increase in ultimate strength up to about 1400°C. This was followed by loss of ultimate strength and the onset of plastic deformation, attributed to the increased ductility of the MoW matrix above 1400°C. Chevron notch tests show that failure originates from features with a critical flaw size of ∼30 εm, which is comparable to the mean particle size of the ceramic phase. X‐ray diffraction (XRD) and Williamson–Hall (WH) analysis suggest that residual stress may contribute to the observed strength‐versus‐temperature behavior. [ABSTRACT FROM AUTHOR]

Purpose: As the applications of nuclear technology increase in today's world, radiation protection becomes even more important. Radiation protection is important in medical imaging applications and radiotherapy rooms. Therefore, in this research, we have investigated features of the ionizing radiation shielding of the modified cement composite with iron, strontium, zinc, and zirconium elements in the photon energy range of 15 keV to 10 MeV. Materials and Methods: To extract such features, it is necessary to use a computational method. In this research, we have done all our calculations based on the Geant4 tool based on the Monte Carlo method. This tool is a multipurpose tool that can be used for particle transport calculations such as electrons, protons, neutrons, heavy charged particles, and photons in different environments such as human tissues. Results: The mass attenuation coefficient of the samples was calculated using the Geant4 Monte Carlo simulation tool and compared with the results of the Phy-X program, which was in good agreement. To evaluate the radiation shielding capabilities, other quantities such as the linear attenuation coefficient, the thickness of the tenth value layer, the thermal neutron cross-section, absorption rate of thermal neutrons, and the cross-section of the fast neutron removal are determined. Conclusions: According to the quantitative results, cement composite is more effective in absorbing and weakening gamma and neutrons. Calculations of radiation shielding quantities show that cement composites containing tungsten carbide and thallium oxide waste powder are a suitable combination and a practical material for radiation control. In addition, by returning industrial waste to the production sector, they will also be effective in reducing environmental pollution. In general, the cement composite sample containing iron, thallium, zinc, zirconium, tungsten, and carbon elements shows a high potential for radiation protection applications. This study highlights the effective radiation shielding potential of cementitious composites and demonstrates the importance of advancing safety measures in medical and industrial radiation applications. [ABSTRACT FROM AUTHOR]

This perspective article delves into the transformative potential of alkali‐activated materials, acid‐activated materials, and geopolymers in mitigating climate change and market challenges. To harness the benefits of these materials, a comprehensive strategy is proposed. This strategy aims to integrate these materials into existing construction regulations, facilitate certification, and promote market access. Emphasizing research and innovation, the article advocates for, increased funding to refine the chemistry and production of these materials, prioritizing low‐cost alternatives and local waste materials. Collaboration between academia and industry is encouraged to expedite technological advances and broaden applications. This article also underscores the need to develop economic and business models emphasizing the long‐term benefits of these materials, including lower life‐cycle costs and reduced environmental impact. Incentivizing adoption through financial mechanisms like tax credits and subsidies is suggested. The strategy also includes scaling up production technology, fostering industrial collaboration for commercial viability, and developing global supply chains. Educational programs for professionals and regulators are recommended to enhance awareness and adoption. Additionally, comprehensive life‐cycle assessments are proposed to demonstrate environmental benefits. The strategy culminates in expanding the applications of these materials beyond construction, fostering international collaboration for knowledge sharing, and thus positioning these materials as essential for sustainable construction and climate change mitigation. [ABSTRACT FROM AUTHOR]

This review covers recent compositions of bioactive glass, with a specific emphasis on both inorganic and organic materials commonly utilized as matrices for injectable materials. The major objective is to highlight the predominant bioactive glass formulations and their clinical applications in the biomedical field. Previous studies have highlighted the growing interest among researchers in bioactive glasses, acknowledging their potential to yield promising outcomes in this field. As a result of this increased interest, investigations into bioactive glass have prompted the creation of composite materials and, notably, the development of injectable composites as a minimally invasive method for administering the material within the human body. Injectable materials have emerged as a promising avenue to mitigate various challenges. They offer several advantages, including minimizing invasive surgical procedures, reducing patient discomfort, lowering the risk of postoperative infection and decreasing treatment expenses. Additionally, injectable materials facilitate uniform distribution, allowing for the filling of defects of any shape. [ABSTRACT FROM AUTHOR]

Quantum‐mechanical calculations based on the density functional theory (DFT) enable an effective characterization of a variety of properties of materials at the atomistic level, although at a high computational cost. Here, we fully exploit parallel computing to apply such methods to the study of lattice dynamics and mechanical response of the major oxide constituents of Portland cement clinker: C3S${\rm {C}}_3{\rm {S}}$, C2S${\rm {C}}_{2}{\rm {S}}$, C3A${\rm {C}}_{3}{\rm {A}}$, and C4AF${\rm {C}}_4{\rm {AF}}$. Raman spectra and the evolution of the elastic tensor (and associated mechanical properties) with pressure are predicted for all oxide systems. We devote much attention to the assessment of dynamical and mechanical stability of the many previously proposed polymorphic forms of the most abundant oxide: C3S${\rm {C}}_3{\rm {S}}$. Specifically, five different crystalline models of C3S${\rm {C}}_3{\rm {S}}$ are analyzed: only two turn out to be dynamically stable. The mechanical response of C3S${\rm {C}}_3{\rm {S}}$ is further analyzed as a function of temperature through a quasi‐harmonic description of its lattice dynamics. [ABSTRACT FROM AUTHOR]

Durability is crucial for reinforced concrete, directly influencing the service life of structures. The presence of aggressive agents, especially chloride ions, significantly impacts durability. This study investigates the differences between ASTM C1202 and IBRACON/NT Build 492 standards in concrete containing various types of cement designed for a characteristic compressive strength of 40 MPa. Forty-eight cylindrical samples were prepared using eight types of Portland cement, including those with blast furnace slag, filler, and pozzolanic materials. Chloride migration tests were performed according to the ASTM C1202/2022 and IBRACON/NT Build 492/1999 methodologies. At a 95% confidence level, the results indicated that concrete made with filler-containing cement (PCII F-SR and PC II F) showed the poorest chloride resistance, with charge passing values exceeding 4000 coulombs (ASTM C1202) and diffusion coefficients above 10 × 10−12 m2/s (IBRACON/NT Build 492). In contrast, concrete containing high slag cement (PC III-SR) and pozzolan cement (PC IV) demonstrated superior resistance to chloride penetration, with charge passing values below 1500 coulombs and diffusion coefficients under 5 × 10−12 m2/s. Notably, discrepancies in classification were observed, as PC II Z (fly-ash based) and PC II E-SR (slag-based) received different ratings under the two methods. ASTM C1202 was found to be more stringent than NT Build 492, highlighting significant variations in the classification criteria between these standards. Based on the findings, new interval values are proposed for classifying concrete regarding the risk of chloride ion penetration, particularly for the ASTM C1202 standard, in order to better align with performance-based durability criteria and improve classification accuracy.

Introduction: Glass-ionomer (GIC) cement was introduced in 1972 as a “new filling material of dentistry”. It is bioactive and plays an important role in caries prevention due to its ability to release fluoride into the oral environment and remineralization of dental hard tissues. However, its properties such as moisture sensitivity, wear resistance, and bond strength are not sufficient to inflict the antimicrobial environment. This in vitro study aimed to evaluate the antibacterial property of four different GIC cements against S. mutans and L. acidophilus. Methodology: This study was conducted on 120 disk-shaped samples (30 for antibacterial activity), which were placed in Petri dishes holding Müeller Hinton agar. Bacterial strains were overhauled in the brain heart infusion culture medium, and by utilizing disposable straps on blood agar medium, 100 μl of the strain inoculum was plated out. Through the diffusion method on the solid medium, the antibacterial activity of GIC was determined. Results: The antibacterial activity was the highest for Riva silver and chemifill rock for 24 and 72 hours, respectively. For 48 hours, Equia forte and chemifill rock had the highest antibacterial activity, and there was a significant difference between the groups. Conclusion: KetacTM molar easymix inhibited the growth of S. mutans and L. acidophilus but had the lowest antibacterial effect compared to other GICs.

Understanding and predicting process–structure–property–performance relationships for concrete materials is key to designing resilient and sustainable infrastructure. While machine learning has emerged as a powerful tool to supplement empirical analysis and physical modeling, its capabilities are yet to be fully realized due to the massive data requirements and generalizability challenges. To address these limitations, we propose a knowledge‐informed machine learning framework for concrete property prediction that aggregates the wealth of domain knowledge condensed in empirical formulas and physics‐based models. By integrating the knowledge through data augmentation, feature enhancement, and model pre‐training, we demonstrate that this framework has the potential to (i) accelerate model convergence, (ii) improve model performance with limited training data, and (iii) increase generalizability to real‐world scenarios (including extrapolation capability to other datasets and robustness against data outliers). The overall improvement of machine learning models by knowledge integration is particularly critical when these models are scaled up to tackle the increasing complexity of modern concrete and deployed in practical applications. While demonstrated for predicting concrete strength, this versatile framework is applicable to a wide range of properties of concrete and other composite materials, paving the way for accelerated materials design and discovery. [ABSTRACT FROM AUTHOR]

The climate is changing rapidly due to anthropogenic greenhouse gases. Glass is a significant contributor to these emissions, with 95 million tons of CO2 being emitted due to glass manufacturing in recent years. Furthermore, glass recycling remains poor in the United States, and most glass is left to landfill after a single use. The lack of recycling and the carbon footprint of manufacturing have made glass an environmentally damaging material despite its theoretical infinite recyclability. Additionally, glass has the potential to enable next‐generation energy materials, enabling the necessary technology for a green economy. In this review, we briefly cover the challenges of glass manufacturing and how to make glass the benchmark material for a carbon‐neutral economy. [ABSTRACT FROM AUTHOR]

The Mars 2020 Perseverance rover has examined and sampled sulfate‐rich clastic rocks from the Hogwallow Flats member at Hawksbill Gap and the Yori Pass member at Cape Nukshak. Both strata are located on the Jezero crater western fan front, are lithologically and stratigraphically similar, and have been assigned to the Shenandoah formation. In situ analyses demonstrate that these are fine‐grained sandstones composed of phyllosilicates, hematite, Ca‐sulfates, Fe‐Mg‐sulfates, ferric sulfates, and possibly chloride salts. Sulfate minerals are found both as depositional grains and diagenetic features, including intergranular cement and vein‐ and vug‐cements. Here, we describe the possibility of various sulfate phases to preserve potential biosignatures and the record of paleoenvironmental conditions in fluid and solid inclusions, based on findings from analog sulfate‐rich rocks on Earth. The samples collected from these outcrops, Hazeltop and Bearwallow from Hogwallow Flats, and Kukaklek from Yori Pass, should be examined for such potential biosignatures and environmental indicators upon return to Earth. Plain Language Summary: Images and compositional data of Mars rocks taken by the Mars 2020 Perseverance Rover at Hogwallow Flats and Yori Pass in Jezero crater show an abundance of sulfate minerals. The goal of this study was to describe the characteristics of these rocks with close‐up views of places where these rocks were abraded to expose fresh rock surface, and to make preliminary interpretations of any preservation potential of any possible environmental and biosignature data. We found sand and silt grains with a variety of colors, some of which are sulfate minerals. We also found sulfate mineral crystals between and cross‐cutting the grains. The sulfate sand and silt grains may have originally grown as chemical sediments in past salty lakes, and the sulfate crystals found between and cross‐cutting the grains formed from past salty groundwater. Sulfate mineral grains and crystals on Earth contain fluid and solid inclusions, which are remnant water, air and other gases, other minerals, and microorganisms and organic compounds. From this knowledge of terrestrial sulfate minerals, we suggest that samples of Hogwallow Flats and Yori Pass, if returned to Earth, should be investigated for fluid and solid inclusions to be evaluated for any enclosed past Martian water, gas, minerals, and possible biosignatures. Key Points: We describe sub‐mm scale observations for abrasion patches Berry Hollow and Uganik Island at Hogwallow Flats and Yori Pass on the western fan front in Jezero craterThese are sulfate‐rich clastic rocks with various diagenetic features that suggest sulfate‐rich surface waters and groundwaterEnvironmental data, such as parent water temperatures and compositions, and any potential biosignatures, may have been preserved [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of composite cement components and thermocycling on the bond strength of monolithic lithium-disilicate (LS2) glass-ceramic implant-supported restorations bonded to titanium (Ti) abutments. Materials and Methods: Eighty LS2 blocks were treated with five types of composite cement and primer, then divided accordingly into groups: M (Multilink hybrid abutment), G (G-CEM LinkAce), GP (G-CEM LinkAce with G-Multi PRIMER), P (Panavia F2.0), and U (RelyX U200). Half of the 16 specimens from each group were subjected to thermocycling (groups T-M, T-G, T-GP, T-P, and T-U). The tensile bond strength (TBS) of all specimens was measured using a pull-off test. The cross section of the LS2 block from which the Ti abutment was removed was examined for mode of failure. Two-way ANOVA and Tukey’s HSD test (significance level = 0.05) were used to determine the effect of composite cement composition and thermocycling on TBS. Results: There was no difference in TBS between the five groups before thermocycling (p = 0.16). However, groups M (p < 0.001) and G (p = 0.014) showed significantly lower TBS than the corresponding thermocycled groups. Groups T-GP, T-P, and T-U did not show significant changes in TBS after thermocycling (p > 0.05). All failures occurred at the interface between the composite cement and Ti abutment and not between the cement and the LS2 block. Conclusion: Thermocycling can reduce the bond strength between the composite cements and Ti abutment. The composite cements containing 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) or methacrylate phosphate ester monomers stabilize bonding. [ABSTRACT FROM AUTHOR]

In order to help dentists in choosing the right type of cement for implant-based prostheses, the radiopacity of commonly used cements available in the market was investigated by digital radiography with PSP sensor. In the present study, temporary cements of TempBond (Kerr, Germany), TempBond clear (Kerr, Germany), Dycal (Dentsply, USA) and permanent cements of Multilink N (Ivoclar, Brazil), Panavia F 2.0 (Kurrary, Japan), Fuji plus (GC, Japan), RelyX (3M, USA), Durelon (3M, USA) were used. Four pill-like samples with 0.5 mm and 1 mm thickness and 5 mm in diameter inside the silicon index as recommended by the manufacturer were prepared for each cement. Aluminum step wedge (99% aluminum alloy) was used as control. Using digital radiography, cement and aluminum step wedge samples were radiographed. The images of cement tablets were measured by digital radiography using DFW software to check their radiopacity values. Bonferroni test and Mann-Whitney U test were used for comparison of cements. The highest radiopacity between the group of 1 and 0.5 mm thickness was related to Glass ionomer Fujiplus GC (2407±45..99) and TempBond (137.21±22.46) cement, respectively. Whereas, the lowest radiopacity among the groups was related to Clear cement. The difference between the mean radiopacities among the studied groups was statistically significant (p<0.001). Based on the results, among the available cements, Glass ionomer Fujiplus GC and TempBond cement are the most efficient for 1 and 0.5 mm thickness, respectively, and Clear cement is the least efficient cement in both groups in terms of radiopacity. [ABSTRACT FROM AUTHOR]

Judicious selection of constituents for concrete composite can minimize the concentration of induced radio-isotopes in the shielding components around the beam loss points of an accelerator. In the present work, 18 concrete composites were prepared using different rock aggregates and cements. Samples were irradiated in the fast neutron environment to estimate the induced short-lived isotopes. Study identified least production of 24Na, 56Mn isotopes in the composite prepared using calcitic marble and white Portland cement. Utilization of this concrete composite mixture can minimize the induced isotope production, specifically at high neutron fluence regions to reduce the occupational exposures during maintenance operations. Article highlights: • Selection of potentially low induced activity generating raw materials are recommended. • Rock aggregates and cements depending on radiation type and energy can generate 24Na and 56Mn. • Composites with calcitic marble and white Portland cement can be used as strippable shielding layer. [ABSTRACT FROM AUTHOR]

Due to its unique properties, zirconia is increasingly being used in dentistry, but surface preparation for bonding is difficult because of its polycrystalline structure. This study aimed to determine the effect of a new etching technique (Zircos-E) on Ceramill Zi (Amann Girrbach). The effect of etching and the use of primers (Monobond Plus and MKZ Primer) on the bond strength of zirconia with resin cement (NX3) was assessed. Shear bond strength was evaluated after storage in water for 24 h and after thermal aging (5000 thermocycling at 5 °C/55 °C). A scanning electron microscope (Hitachi S-4700) was used to evaluate the surface structure before and after the Zircos-E system. The roughness parameters were assessed using an SJ-410 profilometer. The etched zirconia surface is more homogeneous over the entire surface, but some localized forms of erosion exist. The etching of zirconia ceramics caused changes in the surface structure of zirconia and a significant increase in the shear bond strength between zirconia and resin cement. The use of primers positively affects the adhesion between resin cement and zirconia. Aging with thermocycler significantly reduced the shear bond strength, with one exception—sandblasted samples with MKZ Primer. Standard ceramic surface preparation, involving only alumina sandblasting, does not provide a satisfactory bond. The use of etching with the Zircos-E system and primers had a positive effect on the strength of the zirconium–resin cement connection. [ABSTRACT FROM AUTHOR]

In the search for effective biomaterials for bone repair, magnesium phosphate cements (MPCs) are nowadays gaining importance as bone void fillers thanks to their many attractive features that overcome some of the limitations of the well-investigated calcium-phosphate-based cements. The goal of this review was to highlight the main properties and applications of MPCs in the orthopedic field, focusing on the different types of formulations that have been described in the literature, their main features, and the in vivo and in vitro response towards them. The presented results will be useful to showcase the potential of MPCs in the orthopedic field and will suggest novel strategies to further boost their clinical application. [ABSTRACT FROM AUTHOR]

Introduction: Glass-ionomer (GIC) cement was introduced in 1972 as a "new filling material of dentistry". It is bioactive and plays an important role in caries prevention due to its ability to release fluoride into the oral environment and remineralization of dental hard tissues. However, its properties such as moisture sensitivity, wear resistance, and bond strength are not sufficient to inflict the antimicrobial environment. This in vitro study aimed to evaluate the antibacterial property of four different GIC cements against S. mutans and L. acidophilus. Methodology: This study was conducted on 120 disk-shaped samples (30 for antibacterial activity), which were placed in Petri dishes holding Müeller Hinton agar. Bacterial strains were overhauled in the brain heart infusion culture medium, and by utilizing disposable straps on blood agar medium, 100 μl of the strain inoculum was plated out. Through the diffusion method on the solid medium, the antibacterial activity of GIC was determined. Results: The antibacterial activity was the highest for Riva silver and chemifill rock for 24 and 72 hours, respectively. For 48 hours, Equia forte and chemifill rock had the highest antibacterial activity, and there was a significant difference between the groups. Conclusion: KetacTM molar easymix inhibited the growth of S. mutans and L. acidophilus but had the lowest antibacterial effect compared to other GICs. [ABSTRACT FROM AUTHOR]

Ettringite‐accelerated binders composed of CAC–PC–C$ (calcium aluminate cement–Portland cement–calcium sulfate) and CSA–PC–C$ (calcium sulfoaluminate cement–Portland cement–calcium sulfate) have been used widely for indoor applications, such as self‐leveling floor screeds, underlayment, and tile adhesives owing to their rapid setting, early strength gain, and shrinkage compensation properties. These properties also make these binders appealing candidates for outdoor rapid repair (e.g., highways, bridge decks, and airfield pavements). However, a central question remains: Does ettringite remain stable in outdoor exposure conditions? If so, which factors will contribute positively/negatively to the long‐term stability of ettringite in these systems? To address these questions, this critical review presents the current state of knowledge regarding the hydration of ternary binders composed of CAC–PC–C$ and CSA–PC–C$ with respect to ettringite formation and the factors affecting the stability of ettringite thereafter. The purpose of this review paper is to synthesize and analyze current research regarding conditions that promote or deter ettringite stability, establish what information is missing, unclear, or contradictory, and identify remaining research needs to address the identified knowledge gaps. [ABSTRACT FROM AUTHOR]

This study includes the assessment of all possible combinations of ready-mix concrete encompassed in a reference construction database of building materials for Valencia (Spain). All concrete components are considered in the calculation: cement, water, aggregates, and admixtures. The life cycle assessment methodology was used to calculate the environmental impacts of each material, including the modules A1-A3, i.e. production of raw materials, transport, and manufacturing, and impact categories in accordance with EN 15804:2012 + A2:2019. This study shows that cement is the concrete component with the greatest overall impact on the environment. Furthermore, the impact for the Global Warming Potential (stages A1-A3) can double depending on the type of cement; with CEM I and CEM II types having the highest impact. The regressions obtained for each impact category allow to predict the environmental impacts of every ready-mix concrete and also to analyze the relative importance of each concrete component in each impact category. [ABSTRACT FROM AUTHOR]

In order to design lithium-sulfur cells for practical viability in the high-density energy storage, the exploitation of the effective contribution of the large amount of active-material mass to the high specific capacity at a lean-electrolyte condition must be considered. However, this is limited by the insulating nature of solid-state sulfur/sulfide, and the diffusion loss of the liquid-state polysulfides. In this study, Portland cement is adopted as a reinforcement material to design a high-loading polysulfide/cement cathode with sulfur loading and content of 8.64 mg cm−2 and 60 wt%, respectively. The nonporous cement exhibits a high polysulfide-trapping capability and low electrolyte consumption, which enable the high-sulfur-loading cathode to achieve record low electrolyte-to-sulfur ratios of 7–3 μL mg−1, with high gravimetric capacity and areal capacity of the cathode (i.e. , 768 mA h g−1 and 11.06 mA h cm−2, respectively) and dynamically/statically electrochemical stability with 90% capacity retention after 100 cycles and a 1-month rest. [ABSTRACT FROM AUTHOR]

Global cement production has reached 3.9 billion tons. However, the clinkerization process, which is the basis of cement production, is responsible for an approximate annual global CO2 emission of 2 billion tons. As part of CEMBUREAU’s 5C strategy, the European cement industry aims to achieve carbon neutrality throughout the cement-concrete value chain by 2050. This article is a continuation of the previous article on the indirect mechanosynthesis clinkerization process, which combines mechanical activation (high-energy milling) and thermal treatment at lower temperatures (from 900 °C) than those used for conventional clinkerization to produce clinker. With this process, we manufactured cement and clinker from industrial and laboratory raw mixes, which had to be rectified by adding kaolinite in compliance with the different cement indicators (LSF, SM, AM). The cement and clinker produced by indirect mechanosynthesis (15 min of mechanical activation and heat treatment 900 °C or 1200 °C) were characterized. In order to test the hydraulic properties of the cement produced, cement pastes were made. Mechanical and structural studies were carried out (between 70 and 90% of C2S). Mechanical tests revealed for 7 curing days, the values of 3.60 and 7.60 MPa at 900 °C and 1200 °C, respectively, in comparison to commercial cements CEM I and CEM III (23.03 and 19.14 MPa).

The object of the research is cement systems, the materials most commonly used in the construction industry. Since people interact with construction materials all the time, they should only contain harmless components; this requirement applies to modifiers as well. The existing liquefiers are obsolete; there is a need for an alternative composition and production technology. The purpose of the research is, first, to theoretically design the structure of an environmentally friendly plasticizing additive for cement systems based on fragments of natural compounds – lipids and carbohydrates. Secondly, to select a non-pathogenic microbial culture capable of synthesizing this product and the conditions for its fermentation. And finally, to study the properties of cement systems containing the synthesized biomodifier. This paper proposes novel modifiers based on fragments of natural compounds. The production process should be based on biological synthesis running through the cellular structures of microorganisms growing in a synthetic nutrient medium. A non-pathogenic microbial culture was ‘tamed’ to synthesize this product. The authors further designed a synthetic nutrient medium and optimized the fermentation parameters. Ten hours after the onset of fermentation, a fat-like substrate is added to the nutrient medium so that Leuconostoc mesenteroides would be able to synthesize the hypothesized modifier. The output is an efficient glycolipid plasticizer. X-ray diffraction analysis, a plastometer, a flow table, a cone, a viscometer, a versatile press, and an ionometer were used in this research to find the parameters of the synthesized bioadditives and cement systems based on them. The bioplasticizer injection was noted to increase the fluidity of cement mixtures by a factor of 3 to 5. The novel modifiers greatly inhibit early cement hydration when dosed at >0.8 wt.%. However, while inhibiting early structuring, these liquefiers strengthen the material in the long term (3+ months). Injecting these biological additives in the mixture at up to 0.8 wt.% produces a material that is 20÷30 % stronger than the additive-free alternative and absorbs less water while being as resistant to frost. As per our hypothesis, the microbial synthesis did in fact produce efficient cement system modifiers for industrial and residential construction that would be subject to no environmental restrictions.

The speed at which climate change is happening is leading to a demand for new pozzolanic materials that improve the quality of cements and, at the same time, limit the emission of greenhouse gases into the atmosphere. The main objective of this work is the detailed characterization of an ignimbrite sample (IGNS) to demonstrate its effectiveness as a natural pozzolan. To meet this objective, a series of tests were carried out. In the first stage, mineral and chemical analyses were performed, such as petrographic analysis by thin section (TSP), X-ray diffraction (XRD), oriented aggregate (OA), scanning electron microscopy (SEM) and X-ray fluorescence (XRF). In the second stage, the following technical tests were carried out: chemical quality analysis (QCA), pozzolanicity test (PT) and mechanical compressive strength (MS) at 7, 28 and 90 days, using mortar specimens with ignimbrite/cement formulation (IGNS/PC): 10, 25 and 40% to establish the pozzolanic nature of the ignimbrite. The results of the mineral and chemical analyses showed that the sample has a complex mineralogical constitution, consisting of biotite mica, potassium feldspar, plagioclase, smectite (montmorillonite), quartz, volcanic glass, iron, titanium and manganese oxides, chlorite and chlorapatite. On the other hand, the technological tests revealed the pozzolanic nature of the sample, as well as visible increases in the mechanical compressive strengths in the three proportions, the most effective being IGNS/PC:10% and IGNS/PC:25% at 7, 28 and 90 days of setting. The results obtained could be applied in the formulation of new pozzolanic cements with ignimbrite as a natural pozzolanic aggregate. [ABSTRACT FROM AUTHOR]

Osteoporosis is a bone disorder characterised by low bone mineral density, reduced bone strength, increased bone fragility, and impaired mineralisation of bones causing an increased risk of bone fracture. Several therapies are available for treating osteoporosis which include bisphosphonates, anti-resorptive agents, oestrogen modulators, etc. These therapies primarily focus on decreasing bone resorption and do not assist in bone regeneration or offering permanent curative solutions. Additionally, these therapies are associated with severe adverse events like thromboembolism, increased risk of stroke, and hypocalcaemia. To overcome these limitations, bone regenerative pathways and approaches are now considered to manage osteoporosis. The bone regenerative pathways involved in bone regeneration include wingless-related integration site/β-catenin signalling pathway, notch signalling pathway, calcium signalling, etc. The various regenerative approaches which possess potential to heal and replace the bone defect site include scaffolds, cements, cell therapy, and other alternative medicines. The review focuses on describing the challenges and opportunities in bone regeneration for osteoporosis. [ABSTRACT FROM AUTHOR]

The Rocky Point Viaduct, located near Port Orford, OR, was replaced after only 40 years of service. A beam from the original viaduct was studied in detail to determine the mechanisms contributing to severe corrosion damage to the structure. Results are presented from the delamination survey, potential and corrosion mapping, concrete chemistry, and concrete physical properties. The major cause of corrosion damage appears to have been the presence of both pre-existing and environmentally-delivered chlorides in the concrete. [ABSTRACT FROM AUTHOR]

Global cement production has reached 3.9 billion tons. However, the clinkerization process, which is the basis of cement production, is responsible for an approximate annual global CO2 emission of 2 billion tons. As part of CEMBUREAU's 5C strategy, the European cement industry aims to achieve carbon neutrality throughout the cement-concrete value chain by 2050. This article is a continuation of the previous article on the indirect mechanosynthesis clinkerization process, which combines mechanical activation (high-energy milling) and thermal treatment at lower temperatures (from 900 °C) than those used for conventional clinkerization to produce clinker. With this process, we manufactured cement and clinker from industrial and laboratory raw mixes, which had to be rectified by adding kaolinite in compliance with the different cement indicators (LSF, SM, AM). The cement and clinker produced by indirect mechanosynthesis (15 min of mechanical activation and heat treatment 900 °C or 1200 °C) were characterized. In order to test the hydraulic properties of the cement produced, cement pastes were made. Mechanical and structural studies were carried out (between 70 and 90% of C2S). Mechanical tests revealed for 7 curing days, the values of 3.60 and 7.60 MPa at 900 °C and 1200 °C, respectively, in comparison to commercial cements CEM I and CEM III (23.03 and 19.14 MPa). [ABSTRACT FROM AUTHOR]

To investigate the potential mineralising effects of calcium silicate-based dentine replacement material (Biodentine™) in comparison with glass-ionomer cement (GIC) (Fuji IX™) on different human dentine substrates using a multimodal non-invasive optical assessment. Cements were applied on artificially demineralised or naturally carious dentine and stored for 4 weeks in phosphate-rich media +/- tetracycline used for mineralisation labelling. Interfacial dentine was examined from the same sample and location before and after aging using two-photon fluorescence microscopy, fluorescence lifetime imaging (FLIM) and second harmonic generation (SHG) imaging. Additionally, Raman spectroscopy was used to detect changes in the mineral content of dentine. Significant changes in the fluorescence intensity and lifetime were detected in partially demineralised dentine and caries-affected dentine underneath both tested cements, after storage (p < 0.001). This was associated with a significant increase in the mineral content as indicated by the increased intensity of the phosphate Raman peak located at 959 cm−1 (p < 0.0001). Caries-infected dentine showed significant fluorescence changes under Biodentine™ after storage (p < 0.001), but not under GIC (p = 0.44). Tetracycline binding induced a reduction in the fluorescence lifetime with comparable increase in the fluorescence intensity in both cements' groups within the affected dentine (p < 0.001). Significance Two-photon fluorescence microscopy can be used efficiently for non-destructive in-vitro dentine caries characterisation providing a technique for studying the same dentine-cement interface over time and detect changes. Biodentine™ demonstrated comparable remineralising potential to GIC, in addition to inducing remineralisation of caries-infected dentine. This may suggest using Biodentine™ as part of minimally invasive operative dentistry (MID) in caries management. [ABSTRACT FROM AUTHOR]

Currently, one of the primary areas of technical progress in the field of construction is creating modern high performance concretes based on modified cement binders using various chemical and mineral additives that allow effective control of the structure formation and properties of material. The stock of the conventional additives for cement systems is failing to meet the increasing demand, which is related to territorial limitations and high cost of the most popular and efficient mineral modifiers (silica fume, metakaolin, fly ash, granulated slag, etc.). In this respect, thermally activated polymineral clays used as individual mineral additives and in complexes with carbonate rocks are promising for many regions of the Russian Federation, including the Republic of Mordovia. The paper presents results of studying the patterns in which mineral additives obtained on the basis of local raw materials of the Republic of Mordovia (calcined polymineral clay, dolomite and thermally activated mixture of clay and limestone) influence the technological characteristics of plasticized cement paste, phase composition and physical-mechanical properties of cement stone. Optimal dosages of mineral additives of calcined clay and thermally activated mixture of clay and limestone were identified: they did not exceed 19 and 12 % by binder weight, respectively. These dosages improved strength characteristics of cement systems in comparison with the control composition without the additives. X-ray powder diffraction established that using the developed mineral additives based on calcined polymineral clay and carbonate rocks increased hydration rate of Portland cement and allowed a targeted guidance of the cement stone phase composition: optimizing the ettringite concentration, reducing the number of the weakest and corrosion-exposed Portlandite crystals, increasing the density and strength of the bulk of calcium hydrosilicates by shifting the balance towards an increased content of highly dispersive low basic phases of C–S–H(I) type instead of high basic C–S–H(II) compounds. All of these factors determined the chemical efficiency of these mineral modifiers in cement systems.

This paper describes the findings of a study into the impact of the magnitude of induction and the frequency of rotation of an electromagnetic field on the properties of materials (Portland cement, gypsum plaster, limestone), which are treated in the vortex layer machines. The effects were assessed based on the following criteria: 1) the location of the maximum values of the specific surfaces in the factor space as determined by the Tovarov method based on the BET method and the temperature of the model powders following treatment in a vortex layer machine; 2) the symbasis of the change in the values of the specific surface as determined by the BET method and the temperature of the powders following activation. Theoretical and experimental studies have been used as a basis for putting forward the concept of treatment in vortex layer machines. The essence of the concept lies in boosting the defectiveness of particles (i.e. accumulation of defects) followed by defects emerging and particles dispersing. The maximum values of specific surfaces and of the temperature of powder upon activation can be obtained at an electromagnetic field rotation frequency of 66 Hz while the material being treated is mechanically activated at an electromagnetic field induction value of 0.21 T with Portland cement, 0.22 T with gypsum plaster and 0.23 T with limestone. A classification to define the susceptibility of the mineral component to treatment inside vortex layer machines has been proposed.

In the search for effective biomaterials for bone repair, magnesium phosphate cements (MPCs) are nowadays gaining importance as bone void fillers thanks to their many attractive features that overcome some of the limitations of the well-investigated calcium-phosphate-based cements. The goal of this review was to highlight the main properties and applications of MPCs in the orthopedic field, focusing on the different types of formulations that have been described in the literature, their main features, and the in vivo and in vitro response towards them. The presented results will be useful to showcase the potential of MPCs in the orthopedic field and will suggest novel strategies to further boost their clinical application.

• Combined MIP-CT method was developed to explore pore evolution at Mogao Grottoes. • Pores > 355 μm (undetectable by MIP) make up most of pore volume in conglomerate. • Median/mean pore diameters increased by 8–10 times during conglomerate weathering. • Loss of calcite and clay minerals decreased cementation degree during weathering. • Wind erosion and salt weathering caused major cement loss and porosity generation. Numerous conglomerate grottoes have been excavated and preserved in the arid and alkaline regions of NW China. After millennia of weathering, these conglomerate grottoes have suffered from various weathering issues (such as seepage and collapse) that are internally governed by the distribution of pore networks and the degree of cementation. However, studies on conglomerate weathering have mostly been reported in humid and tropical climates, where intensive chemical weathering occurs. Additionally, characterizations of pore evolution during conglomerate weathering have been restricted due to limitations in detecting pore size and pore type using a single pore characterization method. To fill this gap, this study jointly used mercury intrusion porosimetry (MIP) and computed tomography (CT) to characterize the pore evolution process during conglomerate weathering at Mogao Grottoes, a world heritage site in NW China. Mineralogical, hydrological, mechanical and microscopic characterization were also conducted to understand the changes in compositions of bulk samples and cements during weathering. Results revealed that the majority of pores in conglomerate are concentrated in macropores > 5 μm, followed by mesopores and micropores. During weathering, volume fraction of macropores significantly increases and that of micropores decreases, with median/average pore diameters experiencing an 8- to 10-fold increase. Permeability, porosity and fractal dimension exhibited strong positive linear correlations with median/average pore diameters. Throughout weathering, the abundances of calcite and clay minerals show notable decrease, particularly in cements, resulting in an enrichment of feldspars. Frequently occurring sand-carrying wind activities and salt weathering in arid regions are inferred to be responsible for the major cement loss and porosity generation through physical processes. Our combined MIP-CT method for pore network characterization is also applicable to other lithologies with a wide range of pore sizes. The proposed mechanism of pore evolution and cementation failure provides a scientific base for protecting stone heritages in arid zones. [ABSTRACT FROM AUTHOR]

The work is devoted to resource-saving technology development of belite cements. To solve the problem of slow hardening of belite cements, the influence of clinker phases on hydration and structure formation of binders has been studied. Composition and structure of substances were analyzed using X-ray, differential thermal methods and microscopy. Dependence of belite cements’ design strength with a saturation rate of SR = 0.73–0.80 on the content and properties of C3S alite was determined. Increase in C3S activating ability during formation of alite, based on natural silicates structures was revealed. It was found that the combination of C2S belite and calcium silicoaluminate C6A4MS in cement stimulates hydration and hardening processes. Intensive formation of stable hexagonal hydroaluminates and hydrogelenite provides a high rate of structure formation. Advantages of co-hydration of C2S with C3S and C6A4MS were realized in the mixed cement obtained from belite and aluminate clinkers. Studies of clinkers based on skarn-magnetite ore dressing waste indicate the preference of technogenic raw materials for improving belite cements technology.

Tricalcium silicate (C3S) and dicalcium silicate (C2S) are the main components related with the hydration process of mineral trioxide aggregates (MTAs) for endodontic materials. In this study, we investigate the influence of different ratios of C3S and C2S in a series of MTA samples with (100‐x)C3S‐xC2S‐18ZrO2 (x = 0, 10, 15, 34, and 100) on their physical and chemical characteristics, hydration process, and microhardness properties. The chemical compositional properties of different samples are measured using X‐ray diffraction, X‐ray photoelectron spectrometry, and scanning electron microscopy. The physical and microhardness properties are also investigated after the standard hydration process (ISO 6876:2021). Generally, the sample with higher C3S ratio induces the faster hydration, which results in decreased fluidity as well as shorter working and setting times. The microhardness generally decreases with larger C3S ratio. [ABSTRACT FROM AUTHOR]