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This study explores a novel method for fabricating Ca-α-sialon ceramics using a calcium aluminate oxide eutectic additive. Conventional sintering techniques for Ca-α-sialon ceramics employ nitrogen-containing additives to facilitate the Si–N bond substitution mechanism with Al–O and Al–N bonds. In this work, calcium aluminate additives are utilized, leading to the formation of Ca-α-sialon ceramics via carbothermal reduction processes and partial nitridation of aluminum oxide. The influence of varying calcium aluminate content (5, 10, 15, 30, and 40 wt%) on the phase composition of Ca-α-sialon ceramics, produced by hot pressing at 1650 °C in a nitrogen atmosphere, was investigated. Results indicate that increasing the calcium aluminate content leads to the formation of a β-sialon phase, which subsequently transforms into Ca-α-sialon. At 40 wt% calcium aluminate, complete conversion of α-Si 3 N 4 to Ca-α-sialon is achieved, with significant glassy phase formation at the grain boundaries. The study elucidates the relationship between calcium aluminate content, phase composition, lattice parameters, mechanical properties, oxidation resistance, and thermal expansion of the ceramics. [ABSTRACT FROM AUTHOR]

Calcium oxide (CaO) which originated from calcium aluminate cement (CAC, binder) in alumina-magnesia refractory castables significantly deteriorates its high-temperature properties, particularly corrosion resistance. Hence, the development trend of castables is moving towards ultra-low cement and even cement-free castables. In the present work, the influence of different binders, including aluminate cement and alumina-silica gel bonding, on microstructural evolution, thermal-mechanical properties, and corrosion resistance of Al 2 O 3 -MgO castables has been investigated. The obtained results indicated the hot strength of the Al 2 O 3 -MgO cement castables was much higher than that of Al 2 O 3 -MgO castables with gel-bonding. While the latter possessed a better residual strength (9.1 MPa) and residual strength ratio (59.71 %) after thermal-shock testing when compared to the cement bonding sample (6.73 MPa, 50.12 %). Compared to the CACs-bonded samples, slag penetration resistance displayed a notable enhancement in the gel bonding sample. A typical corrosion mechanism based on FactSage® (Version 8.1) thermodynamic simulation was proposed to elucidate the corrosion behavior. [ABSTRACT FROM AUTHOR]

Synthetic textiles such as polyesters are essential for daily life. However, large‐scale production generates large amounts of waste. This study introduces a new approach for valorising polyester textile waste (PTW) by transforming it into a catalyst for biodiesel production via pyrolysis. Specifically, a metal/carbon composite (PTW + steel slag [SS] composite—PSC) with enhanced catalytic properties was prepared by pyrolysing PTW with SS. The alkaline metals in SS facilitate the carbonisation of PTW via decarboxylation, resulting in a PSC rich in carbon, iron, and alkaline compounds. This composite featured mesopores that were larger than the micropores (MPs) typically found in PTW char. The use of porous material (silica) in thermally induced transesterification has been proven to be an efficient method for biodiesel production, achieving a yield of 97.20 wt.% in 1 min (faster than the 93.82 wt.% yields in 60 min observed from conventional alkali‐catalysed transesterification). However, the high reaction temperature (≥ 360°C) poses economic/technical challenges. To overcome this, PSC has been employed as a catalyst in thermally induced transesterification, leveraging its mesoporous structure and high alkaline content, particularly calcium oxide. The PSC achieved a biodiesel yield of 98.10 wt.% at a markedly lower reaction temperature of 120°C within 1 min. This performance was not attainable using silica or PTW char under similar conversion conditions. These findings highlight the potential of PSC produced through the pyrolysis of PTW and SS as effective catalysts for biodiesel production. This process is a promising strategy for converting waste into valuable resources and mitigating the environmental impacts associated with polyester waste. [ABSTRACT FROM AUTHOR]

Hydrothermal degradation deteriorates the fracture toughness and strength of tetragonal stabilised zirconia. The phase transformation to the monoclinic phase is particularly critical for materials with lower stabiliser content such as 2 mol% and 3 mol% yttria stabilised zirconia (2YSZ and 3YSZ). In this work, two routes in two-step sintering and co-doping with calcium oxide are analysed to mitigate the degradation. Both strategies show a reduction in average grain size of the 2YSZ while maintaining a comparable densification. The achieved smaller grains suppress the hydrothermal degradation rates. In addition, a mitigating effect beyond the reduction in grain size of YSZ is found for CaO doping. 1.6 mol% CaO co-doped 2YSZ shows less than 4% of monoclinic phase after 50 h in an autoclave with H 2 O at 134 °C. Pure 2YSZ contrarily reaches 100% monoclinic phase after 20 h at the same conditions. A suppression of degradation by CaO doping was also observed for the composite of nickel oxide and 3 mol% yttria stabilised zirconia. Hence, CaO co-doping can be an interesting strategy to increase resistivity against hydrothermal degradation for both biomedical and renewable energy applications. The findings further outline a route to achieve tetragonal YSZ with lower yttria contents than 2 mol%. • Two approaches were analysed to mitigate hydrothermal degradation in 2YSZ and 3YSZ. • Co-doping with CaO and two-step sintering reduced the grain growth and degradation. • CaO co-doping mitigated the degradation beyond the effect of the grain size. • A complete suppression of degradation was achieved by the addition of 1.6 mol% CaO. • The results show a route to ageing-resistant tetragonal YSZ with lower yttria contents. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of the partial replacement of natural hydraulic lime (NHL) with waste glass powder (GP) on the physical, mechanical, and microstructural properties of NHL mortars. In the experimental study, five mixtures containing up to 50% GP were prepared to evaluate its effect on the flow, carbonation, unit weight, water absorption, porosity, ultrasonic pulse velocity, capillary water absorption, compressive strength, and microstructure of NHL mortars. The experimental results suggest that the partial replacement of NHL with GP significantly affects the properties of NHL mortars. A reduction in compressive strength was observed with increasing GP content in mortars at both early and later stages. Nevertheless, the compressive strength difference between samples containing 50% GP and the reference was found to be relatively minor at 91 days, implying an enhanced pozzolanic reaction over time. The incorporation of GP improved the consistency and capillary water absorption of mortars, while the opposite was observed for ultrasonic pulse velocity, porosity, and water absorption. The microstructural analysis revealed distinct changes in the structure of samples incorporating GP. The partial substitution of hydraulic lime with GP could be beneficial in reducing the CO2 emissions of NHL mortars. [ABSTRACT FROM AUTHOR]

Reducing energy consumption in the building sector has driven the search for more sustainable construction methods. This study explores the potential of cork-modified mortars reinforced with basalt fabric, focusing on optimizing both mechanical and hygroscopic properties. Six mortar mixtures were produced using a breathable structural mortar made from pure natural hydraulic lime, incorporating varying percentages (0–3%) of cork granules (Quercus suber) as lightweight aggregates. Micro-computed tomography was first used to assess the homogeneity of the mixtures, followed by flow tests to evaluate workability. The mixtures were then tested for water absorption, compressive strength, and adhesion to tuff and clay brick surfaces. Adhesion was measured through pull-off tests, to evaluate internal bonding strength. Additionally, this study examined the relationship between surface roughness and bond strength in FRLM composites, revealing that rougher surfaces significantly improved adhesion to clay and tuff bricks. These findings suggest that cork-reinforced mortars offer promising potential for sustainable construction, achieving improved hygroscopic performance, sufficient mechanical strength, internal bonding, and optimized surface adhesion. [ABSTRACT FROM AUTHOR]

The global focus is directed towards extensive ingestion and bioaccumulation of plastic additives and organic dyes such as Tetrabromobisphenol A (TBBPA) and Auramine-O (AO). However, their recalcitrant properties make them toxic chemicals and require an efficient removal strategy based on waste-derived semiconductor nanocomposite. The present study involves the structural configuration of NiFe 2 O 4 created through green methods, integrated into waste shell CaO to create the NiFe 2 O 4 @CaO (NFC) nanocomposite. P-XRD verified the crystalline catalyst, while microscopic examination unveiled spherical NiFe 2 O 4 particles decorating the irregular surface of CaO. The green NFC nanocomposite exhibited superior degradation efficiency for TBBPA (92 %) and AO (95 %) compared to the individual CaO and NiFe 2 O 4 nanoparticles under conditions of minimal pollutant concentration (10 mg L−1), utilizing a catalyst load of 30 mg at neutral pH under natural Sunlight. 1st-order reaction kinetics following early Langmuir adsorption and degradation at optimum conditions. Involvement of •OH, O 2 −•, and holes in the photocatalysis mechanism suggested that hydroxyl radicals significantly contributed to breaking complex molecules of TBBPA and AO, as revealed in Scavenger analysis. The removal of real water samples was also analyzed. The release of TBPPA from underwater, which has toy materials and electric wire materials, was investigated at various time intervals, along with the evaluation of the degradation of the leached TBBPA. Also, NFC has exhibited exceptional sustainability, retaining its usefulness over nine cycles without significant action decreases. In conclusion, the environmentally welcoming NFC is a cost-effective composite for industries and wastewater pollutants removal with good surface properties. [ABSTRACT FROM AUTHOR]

This study investigated the potential of incorporating crushed brick powders (CBPs) and hydrated lime (HL) as additives in concrete production. Various tests were conducted on mortar, paste, and concrete samples to evaluate the performance of different blend types. The results reveal that among 3%, 6%, 9%, and 12% HL additive in the cement-CBP blend, 6% HL addition yields a significant increase in compressive strength of up to 16% compared to the control mortar. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) indicate improved hydration and reduced calcium hydroxide content in CBP-blended pastes, particularly in the blend with 6% HL. The concrete blend incorporating crushed bricks (C-CB) with 6% HL (C-CB-6HL) demonstrates superior early strength gain, surpassing the control blend by approximately 2.1% at 28 days and exhibiting the highest compressive strength at 90 days. It also shows enhanced moisture resistance, with a reduction in water absorption percentage of up to 10.6% compared to the control blend, reduced water permeability, improved resistance against chloride permeability, and better durability against acid attack compared to other blends. Overall, the C-CB-6HL blend shows the most promising durability characteristics, highlighting the potential for sustainable concrete production. Its outcomes have implications for shaping technical standards and promoting sustainable practices in the construction industry, aligning with environmental conservation goals. [ABSTRACT FROM AUTHOR]

The effect of different filler types on the properties of asphalt mortar before and after water saturation was studied by laboratory tests. Under both dry and water-saturated circumstances, four alternative fillers, limestone powder, hydrated lime, PO42.5 cement, and brake pad powder, are used, evaluated, and compared. The study methodology included characterizing the micromorphology, while X-ray diffraction imaging analysis and scanning electron microscopy were used to determine the chemical composition of the asphalt mortar following water saturation. To quantify the effects of moisture on the bonding mechanisms, surface energy concepts were employed to compute the surface free energy parameters of the asphalt mortar made with different filler materials. Dynamic shear rheometry was employed in the investigation to describe the rheological characteristics of the asphalt mortar as a function of filler under different water saturation conditions. The bonding strength of the asphalt mortars with various fillers was then quantitatively measured using pullout tests to account for the coupling effects of moisture and temperature. The findings of the laboratory tests generally showed that the asphalt mortar's effectiveness declined following moisture conditioning and saturation in water. However, hydrated lime, brake pad powder, and cement showed promise in strengthening the bonding of fillers and asphalt, with hydrated lime being superior. Likewise, the asphalt mortar's ability to tolerate moisture and resist water damage was also generally improved by hydrated lime. [ABSTRACT FROM AUTHOR]

Background: Chicken eggshells, a common poultry byproduct, are rich in calcium and provide a sustainable source for producing calcium oxide nanoparticles (CaO NPs). Their use in eco-friendly synthesis aligns with the growing emphasis on sustainable materials for environmental and biomedical applications. Objectives: This study develops an eco-friendly method for synthesizing CaO NPs from chicken eggshells, characterizes their physicochemical properties, and evaluates their antibacterial and antifungal activities. It also tests their effectiveness in removing heavy metal ions (Pb2+, Cr2+, Cd2+, and Hg2+) from aqueous solutions. Methods: CaO NPs were synthesized by calcining chicken eggshells at 700°C for 7 h. Comprehensive characterization included analysis of crystalline structure, morphology, optical properties, bandgap energy, chemical composition, and thermal stability. Antibacterial and antifungal activities were tested using the wellagar diffusion method. Batch adsorption experiments evaluated heavy metal ion removal under varying conditions of pH, temperature, stirring time, and adsorbent concentration Results: The synthesis produced spherical, single-crystal CaO NPs with diameters ranging from 5 to 30 nm and a crystalline size of approximately 20 nm. The nanoparticles had a bandgap energy of about 4.7 eV. Significant antibacterial activity was observed against Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli, with increasing inhibition zones correlating with nanoparticle concentration. The CaO NPs also effectively inhibited Candida albicans. For efficient metal ion removal, the optimal conditions were found to be 30 min at pH 6 with 40 mg of CaO NPs at 25°C, achieving recovery rates of 98% for Pb2+, 97% for Cd2+, 97% for Cr2+, and 97% for Hg2+. For near-complete removal, extending the process to 70 min at pH 6 with 40 mg of CaO NPs at 45°C achieved the highest recovery rates: 99% for Pb2+, 98% for Cd2+, 99% for Cr2+, and 99% for Hg2+, though this approach involves higher energy and cost. Conclusion: CaO NPs derived from chicken eggshells are effective antibacterial agents and adsorbents for heavy metal removal. These findings highlight their potential for sustainable applications in environmental and biomedical fields. [ABSTRACT FROM AUTHOR]

In the present investigation, process parameters were optimized in order to enhance the reduction of calcium oxide (CaO) from sugarcane molasses using acid centrifugation treatment. To predict the effects of process factors on CaO reduction efficiency, a response surface approach with a central composite design was selected. The polynomial quadratic equation was used to predict CaO removal efficiency, and the analysis of variance (ANOVA) test was utilized to assess the relevance of process factors. The appropriateness of the developed model was determined by regression analysis, which yielded a higher R‐squared value of 0.99334 ± 0.01. At the optimum process parameters of 100°C temperature, 50°Bx, and 3.50 pH, the CaO clarification efficacy of 66.17 wt.% was achieved. The experimental results indicated that for acidic centrifugation treatment, the experimentally observed CaO reduction of 65.94 wt% is in close agreement with the model equation's predicted maximum CaO reduction of 66.17 wt% with a t‐test value of 0.497726. Under such conditions, 0.982 wt.% CaO sugarcane molasses was obtained, which is low when compared to the world average of 1.5% CaO content of sugarcane molasses. Furthermore, the implementation of an artificial neural network (ANN) provided a better prediction model for CaO reduction, with a substantial R‐squared value of 0.99866. However, the genetic algorithm (GA) optimization resulted in an actual CaO reduction of 66.21 wt.% with a t‐test value of 0.497726. [ABSTRACT FROM AUTHOR]

This study aims to investigate the relationship between digital printing colour performance and the raw materials used in a matt glaze. Inkjet technology has enhanced the decorative properties of ceramic tiles in production. Improving the colour perception of the glaze is possible by optimizing the raw materials in the glaze, which results in less ink usage and thus lower costs. Investigation of the colour performance of glazes is possible by determining the L* a* b* values of the colours as well as the gamut colour volumes. Colour of the samples were evaluated by spectrophotometer and i1 profiler. Gamut volume was calculated by 3D CIE chromaticity diagrams of ICC profiles. It was observed that the colour saturation was higher in the samples where the pigment was homogeneously distributed in the glaze microstructure. SiO 2 particles not embedded in the glass structure observed in the glaze microstructure disrupt the colour intensity. The low sphere temperature value of the composition made with wollastonite enabled the SiO 2 particles to be embedded in the glaze. When wollastonite was used instead of dolomite as the source of calcium oxide in mat glaze, the colour gamut volume reached its highest value (11262), consequently increasing colour saturation. Conversely, the lowest colour gamut volume (6475) was obtained when dolomite was used instead of wollastonite. [ABSTRACT FROM AUTHOR]

Amongst the many types of food waste, eggshells contain various minerals and bioactive materials, and they can become hazardous if not properly disposed of. However, they can be made useful for the environment and people by being converted to environmentally friendly catalytic materials or environmental purification agents. Simple calcination can enhance their properties and thereby render them suitable for catalytic and environmental applications. This work aimed to prepare CaO from waste eggshells and examine its effectiveness in photocatalytic pollution remediation, electrocatalytic activity, optical sensing, and antibacterial activities. As opposed to other techniques, this calcination process does not require any chemical reagents due to the high purity of CaCO3 in eggshells. Calcium oxide nanoparticles were prepared by subjecting waste eggshells (ES) to high-temperature calcination, and the synthesized CaO nanoparticles were characterized for their structural, morphological, chemical, optical, and other properties. Furthermore, their photocatalytic degradation of methylene blue dye and antibacterial efficiency against Escherichia coli and Staphylococcus aureus were investigated. It was found that the green-converted CaO can be efficiently used in environmental applications, showing good catalytic properties. [ABSTRACT FROM AUTHOR]

Materials for the conservation of cultural heritage must meet specific demands, such as high durability, service life, and compatibility with other materials used in the original building structures. Due to their low permeability to water and water vapor and their high rigidity, the use of Portland cement (PC) mortars, despite their high mechanical resistance and durability, does not represent an appropriate solution for the repair of historic masonry and structures. Their incompatibility with the original materials used in the past, often on a lime basis, is therefore a serious deficiency for their application. On the other hand, lime-based mortars, compared to PC-based materials, are more susceptible to mechanical stress, but they possess high porosity, a high water vapor transmission rate, and moderate liquid water transport. This study aims at the development of two types of lime-based mortars, calcium lime (CL) and hydraulic lime (HL). The modification of mortars was conducted with a carbon-based nanoadditive and graphene nanoplatelets (GNs) in three dosages: 0.1%, 0.3%, and 0.5% of the binder weight. The enhancement of CL mortars by GNs greatly increased mechanical strength and affected heat transport characteristics, while other characteristics such as porosity, water absorption, and drying rate remained almost similar. The application of GNs to HL not only enhanced the strength of mortars but also decreased their porosity, influenced pore size distribution, and other dependent characteristics. It can be concluded that the use of graphene nanoplatelets as an additive of lime-based composites can be considered a promising method to reinforce and functionalize these composite materials. The improved mechanical resistance while maintaining other properties may be favorable in view of the increasing requirements of building materials and may prolong the life span of building constructions. [ABSTRACT FROM AUTHOR]

The increasing incidence of heat stress due to global climate change poses a significant challenge to avocado (Persea americana) cultivation, particularly in regions with intense solar radiation. This review evaluates sun protection strategies, focusing on the efficacy of different sunscreen products such as kaolin, titanium dioxide, and calcium oxide in mitigating thermal stress in avocado trees. The application of these materials was shown to reduce leaf and fruit surface temperatures, improve photosynthetic efficiency, and enhance fruit quality by preventing sunburn and dehydration. Despite these benefits, challenges remain, including the optimal timing and dosage of application, and the potential residue impacts on fruit marketability. The review emphasizes the need for ongoing research to develop more effective formulations and to integrate these sun protection strategies with other agronomic practices. The role of extension services in educating producers about the proper use of these technologies is also highlighted as crucial for the successful adoption of sun protection measures in avocado farming. [ABSTRACT FROM AUTHOR]

Green processes for synthesizing nanocomposites are a hot area of research today as traditional processes are expensive, inefficient, harmful for synthesizing organic and inorganic molecules, and unsuitable for large-scale operations. The present study investigates the capacity of green synthesized Calcium oxide nanoparticles (CaO NPs) for efficiently removing Rhodamine B. Chemical reduction was replaced with Mulberry (Morus nigera) leaf extract as an environmentally friendly reaction mechanism. CaO NPs are characterized by various analytical techniques including EDX, BET, SEM, FTIR, TGA, Zeta Potential, Point of Zero Charge (PZC), and XRD. Maximum adsorption of Rhodamine B by CaO NPs is revealed at an initial concentration of Rhodamine B of 80 ppm, a temperature of 343 K, and contact time of 60 min, 0.4 g of adsorbent at a pH value of 7. Maximum removal of Rhodamine B by CaO NPs was found to be 98.2% which is promising with this small amount of adsorbent (0.4 g). Diverse Kinetic and adsorption isotherms are employed in this study to determine the requirement and significance of the adsorption process. Various adsorption isotherms such as Freundlich, Temkin, Dubinin–Radushkevich (D–R), and Langmuir models have been employed. Among the kinetic adsorption isotherms Elovich, Intraparticle kinetic model, pseudo 1st order, and pseudo 2nd order models were applied. The current study investigates the thorough understanding of the Rhodamine B adsorption process including the mechanism of adsorption using condition optimization, characterization, and model applications. The proposed adsorbent can be employed for the green removal of Rhodamine B from wastewater of industry with maximum efficiency and favorable regeneration properties. [ABSTRACT FROM AUTHOR]

The clean and efficient utilization of coal is a promising way to achieve carbon neutrality. Coking coal is a scarce resource and an important raw material in the steel industry. However, the presence of pyrite sulfur affects its clean utilization. Nonetheless, this pyrite could be removed using depressants during flotation. Commonly used organic depressants (sodium lignosulfonate (SL), calcium lignosulfonate (CL), and pyrogallol (PY)) and inorganic depressants (calcium oxide (CaO) and calcium hypochlorite (Ca(ClO)2)) were chosen in this study. Their inhibition mechanism was discussed using FTIR, XPS, and molecular dynamics (MD) methods. The desulfurization ability of organic depressants was shown to be better than inorganic ones. Among the organic depressants, PY proved to be advantageous in terms of low dosage. Physical adsorption was identified as the main interaction form of SL, CL, and PY onto the surface of pyrite, as evidenced from FTIR and XPS analyses. Similarly, MD simulation results showed that hydrogen bonds played a proactive role in the interactions between PY and pyrite. The diffusion coefficient of water molecules on the pyrite surface was also observed to decrease when organic depressants were present, indicating an increase in the hydrophilicity of pyrite. This research is of great significance to utilize sulfur-containing coal and minerals. [ABSTRACT FROM AUTHOR]

Phosphogypsum is a common industrial solid waste that faces the challenges of high stockpiling and low utilization rates. This study focuses on the mechanical properties and internal characteristics of cementitious materials with a high phosphogypsum content. Specifically, we examined the effects of varying amounts of ground granulated blast furnace slag (5–28%), fly ash (5–20%), and hydrated lime (0.5–2%) on the stress–strain curve, unconfined uniaxial compressive strength, and elastic modulus (E50) of these materials. The test results indicate that increasing the ground granulated blast furnace slag content can significantly enhance the mechanical properties of phosphogypsum-based cementitious materials. Additionally, increasing the fly ash content can have a similar beneficial effect with an appropriate amount of hydrated lime. Furthermore, microscopic analysis of the cementitious materials using a scanning electron microscope revealed that the high sulfate content in phosphogypsum leads to the formation of calcium aluminate as the main product. Concurrently, a continuous reaction of the raw materials contributes to the strength development of the cementitious materials over time. The results could provide a novel method for improving the reusing phosphogypsum amount in civil engineering materials. [ABSTRACT FROM AUTHOR]

The deposition of Yellow River sediment in the middle and lower reaches is a significant factor in the siltation of reservoirs and the occurrence of serious flooding along the river. The efficient and valuable utilization of Yellow River sediment has already become a key research topic in this field. In this study, we have employed Yellow River sediment as the primary material, in conjunction with commercially available slag, fly ash, and quicklime as the binder, to develop a novel type of artificial flood-prevention stone. Following a 28-day standard curing procedure, the highest compressive strength of the prepared artificial stone was recorded at 4.29 MPa, with a value exceeding 0.7 MPa under wet conditions. The results demonstrated that the prepared artificial stone met the specifications for artificial flood-prevention stones. The curing mechanism, as evidenced by analyses from SEM and XRD testing, indicated that the alkali excitation process in the binder, which produced C-A-S-H gel, was the key factor in enhancing the compressive strength of the specimens. Notably, an evaluation of the amount of CO2 emissions and the cost of the artificial stone concluded that the preparation process was both environmentally friendly and cost-effective. [ABSTRACT FROM AUTHOR]

Rotary hearth furnaces and rotary kilns are the mainstream methods for large-scale treatment of electric furnace dust (EAFD) in steel companies, but they require a large amount of energy and have low product quality. The roasting conversion–separation technology uses calcium oxide to promote the conversion of zinc–iron spinel in EAFD into zinc oxide and dicalcium ferrite, but adding calcium oxide additionally increases production costs. Converter sludge (OGS) is rich in iron oxides and valuable components such as CaO, CaCO3, ZnFe2O4, etc. The free calcium oxide and calcium carbonate can be used as substitutes for pure calcium oxide. This paper designed a multi-solid waste collaborative reduction roasting process to realize the recovery of zinc and iron elements from OGS and EAFD and explore the feasibility of industrial treatment in rotary hearth furnace. The results show that harmful OGS can be used as the calcium agent in the roasting process. The calcium carbonate in OGS not only improves the conversion of iron oxide into metallic iron, but the decomposed CaO can promote the conversion of zinc–iron spinel in OGS and improve the dezincification effect. Better conditions are: 60% OGS, nC/nO = 1.2, roasting temperature 1150°C, roasting for 25 min; zinc content in the reduction product is 0.21%, and metallization rate is 78.53%, which can be used as a high-quality substitute or coolant for scrap steel raw materials in the steelmaking process. This process can realize green and comprehensive utilization of EAFD and OGS and is expected to achieve industrialization. [ABSTRACT FROM AUTHOR]

This study is devoted to the synthesis of aerated concrete by a non-autoclave method using ash from thermal power plants and a nanopreparation. Fullerenol-m was used as a nanopreparation. The fullerenol-m content in the sealing water of aerated concrete changed in the range of 0.00 ÷ 0.03 mas.%. The main performance characteristics of the nanostructured aerated concrete were studied, namely the compressive strength, impact toughness, thermal conductivity, density and moisture content. A significant improvement in the performance characteristics of the nanomodified aerated concrete compared to unmodified samples was demonstrated, which was most clearly manifested as an increase in impact toughness by several (three to five) times. The best performance characteristics of the modified aerated concrete were observed at a fullerenol-m concentration relative to the added cement within 0.022–0.028 wt.%. The authors attribute such a strong change and improvement in the physical, chemical and operational properties of aerated concrete when modified with fullerenol-m to the fact that fullerenol-m (a few thousandths of wt.%) has a very strong structuring effect on the sealing water and, as a consequence, on the resulting aerated concrete. [ABSTRACT FROM AUTHOR]

Aging of binders is a complex phenomenon which reduces the longevity of flexible pavements. Aging involves change in physical, chemical, and morphological properties of binder which makes the binder brittle and highly susceptible to fatigue and thermal cracking. Antiaging additives enhance the service life of flexible pavements by reducing the impact of aging on the performance of binders. An iterative approach is essential to identify the optimal dosage of antiaging additive necessary to counteract the aging effects on binder. The present study aims to evaluate the mixing conditions for uniform dispersion of carbon black and hydrated lime within the binder matrix and thereby evaluate the impact of incorporating these antiaging additives on the conventional properties of binder. For this purpose, varying proportions of carbon black and hydrated lime are added to VG 30 binder and is subjected to softening point, ductility, and penetration tests. The optimal dosage of carbon black and hydrated lime is found to be 6 and 12% respectively based on their significant effects on the conventional properties of the binder. An optimal mixing duration of 60 and 75 min ensures uniform dispersion of carbon black and hydrated lime within the binder matrix at a mixing temperature of 120 °C and a speed of 1000 rpm thereby producing a homogenous binder mastic. Incorporation of antiaging additives up to the optimal dosage enhances the softening point whereas decreases the penetration and ductility of binder. The increase in softening point of binder with incorporation of carbon black and hydrated lime signifies enhanced resistance to rutting and permanent deformation of binder, whereas the reduction in ductility and penetration of binder with incorporation of carbon black and hydrated lime signifies the reduced susceptibility of binder to environmental factors such as temperature fluctuations, UV radiation, and oxidation. The surface texture of the additive influences the ability of binder adsorption, which subsequently affects the rheological properties of binder mastics. Significant improvement in conventional properties of binder with incorporation of carbon black and hydrated lime paves a viable and cost-effective solution for engineering application as it has a subsequent effect on the rheological properties of binder. [ABSTRACT FROM AUTHOR]

This paper proposes a mechanical dispersion method of hydrated lime in a vibrating activator equipped with special blades that operate in a resonant mode. It has been found that during the vibro-activation process, hydrated lime consistently passes through proportionately increasing stages of dynamic viscosity, slowing its growth and ceasing dispersion. A new vibration method for determining the viscosity of the hydrated lime-water system has been developed. The effect of vibration treatment on changes in the dispersion of calcium hydroxide was studied. It has been found that vibration-treated lime, compared to conventional hydrated lime, has new properties: the ability to form durable coatings due to accelerated carbonization. [ABSTRACT FROM AUTHOR]

This study aimed to compare calcium oxide (CaO) and calcium chloride (CaCl2) as calcium sources for coconut fatty acid distillate (CFAD) calcium soap (Ca-soap) production and to evaluate the supplementation ratios of unprotected and protected CFAD in dairy rations to optimize rumen function. This research included two steps: (1) assessing the protection strength of Ca-soap made with CaO and CaCl2 at mole ratios of Ca to CFAD of 1, 1.5, 2, and 2.5; (2) evaluating CFAD supplementation in an in vitro dairy ration study using a 5 × 4 randomized factorial block design. Factor A compared unprotected and protected CFAD ratios of A1 = 100:0, A2 = 75:25, A3 = 50:50, A4 = 25:75, and A5 = 0:100, and factor B compared supplementation levels of B1 = 0%, B2 = 1%, B3 = 2%, and B4 = 3%. CaCl2 at a 2.5-mole ratio to CFAD produced the lowest acid value and the carboxylic acid (C=O) chemical bond. Complete protection (0:100) exhibited the highest densities of Bacteroides and nutrient digestibility (p < 0.05) without significantly affecting rumen fermentability (p > 0.05). Higher CFAD levels significantly reduced methanogens and protozoa (p < 0.05) without significantly affecting estimated methane production. In conclusion, CaCl2 at a 2.5-mole ratio to CFAD provided the best protection, and its complete protection in CFAD supplementation optimized rumen function. [ABSTRACT FROM AUTHOR]

The construction sector is among the most polluting industries globally, accounting for approximately 37.5% of the European Union's total waste generation in 2020. Therefore, it is imperative to develop strategies to enhance the sustainability of this sector. This paper proposes a multiscale COMSOL Multiphysics numerical model for an ex situ mineral carbonation process of hydrated lime. The carbonation process is characterized at both the micro- and macroscale levels, encompassing interactions within and between the particles. This model incorporates both reaction and diffusion phenomena, considering the effects of porosity and liquid-water saturation parameters. Generally, liquid-water saturation enhances the reaction kinetics but not CO2 diffusion, while porosity improves CO2 diffusion throughout the granular bed. The model has been experimentally validated, showing promising results by accurately characterizing carbonation tendencies and the influence of the CO2 flow rate and the initial water-to-solid ratio on the carbonation process. The proposed mathematical model facilitates the study of various parameters, including particle radius, reactor geometry, and material porosity. This analysis is valuable for both current and future projects, as it aims to identify the most profitable configurations for the hydrated lime carbonation process. [ABSTRACT FROM AUTHOR]

A heterogeneous base catalyst transesterification process with a calcium oxide (CaO) catalyst was performed to produce high-purity methyl ester (ME) from pretreated sludge palm oil (PSPO) derived from sludge palm oil (SPO). Additionally, a comparative analysis was conducted with potassium hydroxide (KOH) as a homogeneous base catalyst to assess the distinctions between heterogeneous and homogeneous base catalysts. The response surface methodology (RSM) was utilized to determine the optimal and recommended conditions for both transesterification processes. For heterogeneous transesterification, a varying CaO catalyst loading (10–60 wt.%), methanol (25–65 wt.%), and reaction time (60–180 min) were essential parameters. Meanwhile, homogeneous transesterification involved investigating the KOH catalyst loading (1–3 wt.%), methanol (1.8–5.5 wt.%), and reaction time (20–60 min). For the heterogeneous-base-catalyzed reaction, the recommended conditions were as follows: a molar ratio of methanol to oil of 5.83:1 (41.61 wt.%), 31.3 wt.% CaO, and a reaction time of 119.0 min, which resulted in a ME purity of 96.51 wt.%. The optimal conditions for homogeneous transesterification were a molar ratio of methanol to oil of 0.49:1 (3.45 wt.%), a 40 min reaction time, and a 1.39 wt.% KOH concentration, which achieved 96.59 wt.% ME and met the standard. [ABSTRACT FROM AUTHOR]

Simple Summary: Fluctuations of physiological characteristics play an important role in a living organisms' normal existence and adaptation to environmental conditions. An important feature of oscillations in living systems is their ability to form (synchronization) or break links (desynchronization) with each other. For example, synchronization/desynchronization in the brain's electrical activity plays a role in memory and learning; synchronization changes cause epilepsy and other diseases. The task of quantifying the synchronization of signaling events in cells is currently unsolved. No universal, informative and accurate method has been found for assessing the synchronization of large cell groups. For the first time, we have tested the possibility of applying a mathematical method called bispectral analysis (applied earlier on the whole organism) to assess the coupling of signaling molecules and the level of fluctuations in cells. This method allows for a highly accurate estimation of the connection of oscillations between all pairs of cells in a studied population, the magnitude and frequency of these coupled oscillations, and which cells create and receive a "signal to form a connection of oscillations". We have shown that stress (overheating and excessive glucose concentration) changes the synchronization of oscillations of signaling molecules in cells. The obtained data can be applied in medicine and human economic activity. The oscillation synchronization analysis in biological systems will expand our knowledge about the response of living systems to changes in environmental conditions. This knowledge can be used in medicine (diagnosis, therapy, monitoring) and agriculture (increasing productivity, resistance to adverse effects). Currently, the search is underway for an informative, accurate and sensitive method for analyzing the synchronization of oscillatory processes in cell biology. It is especially pronounced in analyzing the concentration oscillations of intracellular signaling molecules in electrically nonexcitable cells. The bispectral analysis method could be applied to assess the characteristics of synchronized oscillations of intracellular mediators. We chose endothelial cells from mouse microvessels as model cells. Concentrations of well-studied calcium and nitric oxide (NO) were selected for study in control conditions and well-described stress: heating to 40 °C and hyperglycemia. The bispectral analysis allows us to accurately evaluate the proportion of synchronized cells, their synchronization degree, and the amplitude and frequency of synchronized calcium and NO oscillations. Heating to 40 °C increased cell synchronization for calcium but decreased for NO oscillations. Hyperglycemia abolished this effect. Heating to 40 °C changed the frequencies and increased the amplitudes of synchronized oscillations of calcium concentration and the NO synthesis rate. The first part of this paper describes the principles of the bispectral analysis method and equations and modifications of the method we propose. In the second part of this paper, specific examples of the application of bispectral analysis to assess the synchronization of living cells in vitro are presented. The discussion compares the capabilities of bispectral analysis with other analytical methods in this field. [ABSTRACT FROM AUTHOR]

To improve the resource utilization of dredged silt and industrial waste, this study explores the efficacy of using ground granulated blast furnace slag (GGBS), active calcium oxide (CaO), and sodium silicate (Na2O·nSiO2) as alkali activators for silt stabilization. Through a combination of addition tests, response surface method experiments, and microscopic analyses, we identified key factors influencing the unconfined compressive strength (UCS) of stabilized silt, optimized material ratios, and elucidated stabilization mechanisms. The results revealed the following: (1) CaO exhibited the most pronounced stabilization effect, succeeded by Na2O·nSiO2, whereas GGBS alone displayed marginal efficacy. CaO-stabilized silt demonstrated rapid strength augmentation within the initial 7 d, while Na2O·nSiO2-stabilized silt demonstrated a more gradual strength enhancement over time, attributable to the delayed hydration of GGBS in non-alkaline conditions, with strength increments noticeably during later curing phases. (2) Response surface analysis demonstrated substantial interactions among GGBS-CaO and GGBS-Na2O·nSiO2, with the optimal dosages identified as 11.5% for GGBS, 4.1% for CaO, and 5.9% for Na2O·nSiO2. (3) X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses clarified that the hydration reactions within the GGBS-Na2O·nSiO2 composite cementitious system synergistically enhanced one another, with hydration products wrapping, filling, and binding the silt particles, thereby rendering the microstructure denser and more stable. Based on these experimental outcomes, we propose a microstructural mechanism model for the stabilization of dredged silt employing GGBS-CaO-Na2O·nSiO2. [ABSTRACT FROM AUTHOR]

This study aims to compare the effects of three calcium compounds on the workability, setting time and mechanical properties of red mud (RM)–blast furnace slag (BFS)-based geopolymers. The crystalline phase, hydration process and microstructure of RM-BFS-based geopolymers were characterized by X-ray diffraction (XRD), heat evolution, X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) tests. The results showed that an appropriate amount of calcium compounds can improve the flowability and compressive strength of the geopolymers, but the excessiveness causes a decrease in strength due to rapid hardening. Other than calcium carbonate, both calcium oxide and calcium chloride played important roles in accelerating the setting times of RM-BFS-based geopolymers. The acceleration in the setting times of geopolymers could be attributed to the calcium hydroxide produced by the dissolution of the calcium compounds, which also provides nucleation sites for the geopolymerization reaction. This study gives new insights into the effect of calcium on the setting times and mechanical properties of geopolymers in the geopolymerization process. [ABSTRACT FROM AUTHOR]

The utilization of biopolymers incorporated with antimicrobial agents is extremely interesting in the development of environmentally friendly functional materials for food packaging and other applications. In this study, the effect of calcium oxide (CaO) on the morphological, mechanical, thermal, and hydrophilic properties as well as the antimicrobial activity of carboxymethyl chitosan (CMCH) bio-composite films was investigated. The CMCH was synthesized from shrimp chitosan through carboxymethylation, whereas the CaO was synthesized via a co-precipitation method with polyethylene glycol as a stabilizer. The CMCH-CaO bio-composite films were prepared by the addition of synthesized CaO into the synthesized CMCH using a facile solution casting method. As confirmed by XRD and SEM, the synthesized CaO has a cubic shape, with an average crystalline size of 25.84 nm. The synthesized CaO exhibited excellent antimicrobial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) (>99.9% R). The addition of CaO into CMCH improved the mechanical and hydrophobic properties of the CMCH-CaO films. However, it resulted in a slight decrease in thermal stability. Notably, the CMCH-CaO10% films exhibited exceptional antimicrobial activity against E. coli (98.8% R) and S. aureus (91.8% R). As a result, such bio-composite films can be applied as an active packaging material for fruit, vegetable, or meat products. [ABSTRACT FROM AUTHOR]

Although soil stabilization with cement and lime is widely used to overcome the low shear strength of soft clay, which can cause severe damage to the infrastructures founded on such soils, such binders have severe impacts on the environment in terms of increasing emissions of carbon dioxide and the consumption of energy. Therefore, it is necessary to investigate soil improvement using sustainable materials such as byproducts or natural resources as alternatives to conventional binders—cement and lime. In this study, the combination of cement kiln dust as a byproduct and zeolite was used to produce an alkali-activated matrix. The results showed that the strength increased from 124 kPa for the untreated clay to 572 kPa for clay treated with 30% activated stabilizer agent (activated cement kiln dust). Moreover, incorporating zeolite as a partial replacement of the activated cement kiln dust increased the strength drastically to 960 and 2530 kPa for zeolite ratios of 0.1 and 0.6, respectively, which then decreased sharply to 1167 and 800 kPa with further increasing zeolite/pr to 0.8 and 1.0, respectively. The soil that was improved with the activated stabilizer agents was tested under footings subjected to eccentric loading. The results of large-scale loading tests showed clear improvements in terms of increasing the bearing capacity and decreasing the tilt of the footings. Also, a reduction occurred due to the eccentricity decreasing as a result of increasing the thickness of the treated soil layer beneath the footing. [ABSTRACT FROM AUTHOR]

Recent seismic events have prompted research into innovative and sustainable materials for strengthening and repairing obsolete and vulnerable buildings. These earthquakes have exposed the high seismic vulnerability of existing reinforced concrete (RC) buildings, particularly in secondary structural elements like infill walls. In addition to structural issues, these buildings often face significant energy deficiencies, such as thermal bridges, due to inadequate insulation. Traditionally, structural and energy improvements for residential buildings are addressed separately with different methods and protocols. This preliminary study is part of a broader research initiative at the University of Reggio Calabria (Italy), aiming to design an innovative fiber-reinforced plaster using natural, sustainable, and locally produced materials to enhance the energy and structural performance of existing wall infills. The study investigates two plaster matrices made of natural hydraulic lime and silica sand, with 15% and 30% cork granules added. Mechanical and thermophysical tests on multiple specimens were conducted to evaluate their suitability for seismic and energy retrofitting of infill walls. Results indicate that adding cork reduces mechanical strength by approximately 42% at a 30% cork content without compromising its use in seismic retrofitting. Thermophysical tests show improved thermal performance with a higher cork content. These findings suggest that the lime–cork mixture at 30% is effective, offering excellent ductility and serving as a promising alternative to traditional cementitious plaster systems. The next experimental phase will test matrices with varying percentages of gorse fiber. [ABSTRACT FROM AUTHOR]

In this work, the effects of the mixing water loss capacity of hydrated lime mortars with different dosages were analysed—type O (mix 1:2:9), type N (mix 1:1:6), and type M (mix 1:0.5:4.5), with additions of submerged arc welding (SAW) slag. Infrared thermography tests and optical and scanning electronic microscopy analyses of the mortars were also carried out. The experimental results showed that the mortar samples with additions of SAW slag type M, using low-cost materials, proved to be in economic and technical terms (adhesion strength) the best solution, even more so if a spatter dash layer is used, a fact that increases the adhesion strength even more. Also, the infrared thermographic results revealed that the ability of the mortar paste to yield water to the ceramic substrate in the interface regions is a relevant factor in the adhesion of these coatings. Finally, the analyses by scanning electron microscopy and optical microscopy revealed that the ability to release water to the substrate is related to the hydration of the mortar and its anchoring capacity. Furthermore, the analyses carried out demonstrated that the adhesion of the mortars is influenced and increased with the application of a layer of splashes, as the pores of the substrate become more refined and better filled with the applied mortar. [ABSTRACT FROM AUTHOR]

Ladle furnace slag (LFS) is used as a supplementary cementitious material (SCM) due to its high calcium oxide (CaO) content. Its binding properties are enhanced in the presence of siliceous materials, such as metakaolin (MK), forming a ternary mixture that can directly replace ordinary Portland cement (OPC). However, despite this blend having already been evaluated in alkali-activated mixtures, knowledge about this mixture in situations of direct replacement of OPC by slag is still lacking. This study evaluates the synergistic effects of combining LFS and MK in cementitious mortars. Due to an insufficient hydration reaction observed in the short term, this study focuses on assessing the long-term performance of these mortars. Both the fresh and hardened states at 28 and 180 days are evaluated, and the resulting microstructural characteristics and constituent phases are also examined. After 180 days of curing, the mortar with MK exhibits superior binding activity compared to the results at 28 days. Although the nominal resistance does not show a clear advantage with the application of MK, a significant reduction in the porosity of the mortar is observed. Microstructural analysis indicates that the addition of MK increases the hydration compounds when mixed with LFS. Importantly, the sample containing MK and LFS showed a 42% reduction in cement consumption, highlighting the potential for resource efficiency. Thus, this study contributes to promoting a circular economy between the steelmaking and civil construction sectors. [ABSTRACT FROM AUTHOR]

This article presents the results of research work devoted to improving the characteristics of paint and varnish coatings based on aqueous dispersions of polyacrylates; it is proposed to modify them by introducing mineral raw materials as fillers and hydrated lime, with subsequent processing in a vortex layer apparatus. The introduction of activated diatomite does not cause the deterioration of covering power, adhesion or an increase in the porosity of the paint material. The modification of coatings contributes to an increase in their operational properties, which can be associated with a reduction in the free volume in the composite and the formation of polymer boundary layers with modified physical and chemical properties. The aim of this study is to obtain a water-dispersion paint and varnish composition containing modified diatomite on a polyacrylate basis and, subsequently, study its main physical and mechanical parameters. The work has been carried out by the following method: determination of porosity, adhesion, elasticity and covering power of the control composition; determination of porosity, adhesion, elasticity and covering power of the obtained composites using modified filler; investigation of the influence of radiation on the infrared spectrum of the paint coating surface using a FLIRB620 thermal imager. As a result of this research work, it was noticed that the modification of water dispersions with silica-activated diatomite helps to eliminate the main disadvantages of materials and coatings based on acrylate binders—low water resistance and low physical and mechanical characteristics. The introduction of modified diatomite into water-emulsion paint on an acrylate base does not lead to the deterioration of the main performance characteristics of paint coatings—porosity, adhesion, elasticity and covering. [ABSTRACT FROM AUTHOR]

Calcium oxide (CaO) nanoparticles have gained wide attention in various environmental applications, including water treatment and microbial pollution control. This research provides novelty in innovating new strategies in water management and waste treatment based on advanced technology with a nanoscience approach by utilizing local resources. This study aims to synthesize CaO nanoparticles using a green chemistry method using a bioreductor from Bitti (Vitex cofassus) plant extract. This green chemistry approach is not only environmentally friendly but also efficient in producing stable nanoparticles with controlled size. Nanoparticle characterization was performed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) to determine their crystal structure, morphology, and particle size. The results showed that calcium oxide nanoparticles have FCC (face-centered cubic) crystal phase, uneven surface morphology, and spherical shape and have an average particle size of 24.87 nm. The antibacterial activity of calcium oxide nanoparticles on Escherichia coli test bacteria with variations in nanoparticle concentrations (1, 3, and 5%) each had an average inhibition zone diameter of 9.59; 10.78; and 11.78 mm, positive control (Chloramphenicol) of 12.65 mm, and negative control (sterile aqua) of 0 mm, while in Staphylococcus aureus test bacteria with nanoparticle concentration variations (1, 3, and 5%) each had an average inhibition zone diameter of 10.26; 11.15; and 14.15 mm, positive control (Chloramphenicol) of 12.82 mm, and negative control (sterile aqua) of 0 mm. CaO nanoparticles have greater effectiveness on Staphylococcus aureus bacteria than Escheria Coli with the ability to inhibit and kill both types of bacteria. The application of these nanoparticles as antibacterial agents can effectively reduce microorganism waste in the aquatic environment, so they have the potential to be used as a solution for environmentally friendly microbial waste treatment. [ABSTRACT FROM AUTHOR]

Limiting global warming to 1.5-2 °C requires a 50-90% reduction in CO2 emissions in 2050, depending on different scenarios, and carbon capture, utilization, and storage is a promising technology that can help reach this objective. Calcium oxide (CaO) carbon capture is an appealing choice because of its affordability, large potential capacity, and ability to withstand the high temperatures of flue gases. However, the structural instability and capacity fading challenge its large-scale industrial applications. Here, we design a reversible reaction shuttle in CaO-based sorbents to improve the structure stability by changing the initial alumina phases. Diverse alumina phases (x-Al2O3) are first synthesized and utilized as the aluminum source for creating CaO@x-Al2O3 composites. As expected, the CaO@δ-Al2O3 composite demonstrates a carbon capture capacity of 0.43 g-CO2/g-sorbent after 50 cycles, with an impressive capacity retention of 82.7%. Combined characterizations and calculations reveal that this stability improvement is attributed to a transition shuttle between Ca3Al2O6 and Ca5Al6O14, which can effectively restrain the complete decompositions of those structure-stabilized intermediate phases. An economic assessment further identifies the significance of heat transfer efficiency improvement upon cycles, and control of capital/operation cost, energy price and carbon tax for a future cost-effective commercialization of current strategy. Distinct alumina phases lead to various intermediate phases in the CaO@x-Al2O3 composites. Here authors show that δ-Al2O3 induces a transition shuttle between Ca3Al2O6 and Ca5Al6O14 in a classical CaO-Al2O3 system, thus improving its carbon capture stabilities. [ABSTRACT FROM AUTHOR]

This study compares the structural, microstructural, thermal, and mechanical properties of geopolymer pastes (GPs) created through traditional methods and those derived from ready-to-use powders for geopolymer (RUPG) materials. The metakaolin (MK) precursor was activated using a sodium silicate solution or CaO and MOH (where M is Na or K). Various ratios of precursor/activator and Na2SiO3 or CaO/MOH were tested to determine the optimal combination. For RUPG, the MK precursor was activated by replacing the sodium silicate solution with quicklime. Metakaolin, alkaline hydroxide, and quicklime powders were mixed at different CaO ratios (wt%) and subjected to extensive ball milling to produce RUPG. The RUPG was then hydrated, molded, and cured at 20 °C and 50% relative humidity until testing. Analytical methods were used to characterize the raw and synthesized materials. Classic geopolymers (CGPs) activated with quicklime burst after one hour of molding. The results indicated slight amorphization of GP compared to raw MK, as confirmed by X-ray diffraction analysis, showing N(K)-A-S-H in CGP and N(K)-A-S-H with calcium silicate hydrate (C-S-H/C-A-S-H) in RUPG. The compressive strength of MK-based geopolymers reached 31.45 MPa and 34.92 MPa for GP and CGP, respectively, after 28 days of curing. [ABSTRACT FROM AUTHOR]

Thermoactivated recycled cement (RC) is a growing area of research and development in the cement industry. The approach represents a reversible process of cement hydration in which dehydrated compounds with similar characteristics to cement are obtained by means of thermal activation. To avoid CO2 emissions during the production of such RC, this study assesses the possibility of replacing ordinary Portland cement (OPC) with hardened cement powder (HCP) prepared with different proportions of hydrated lime (HL), relying on a second pozzolanic reaction, and compares it with RC mortars. Due to the thermal activation of HCP, the compressive strength increases by 11.5%. The addition of 8% HL produced an important increase in strength from 28 days to 90 days by 12.8%, although without surpassing the strength values of mortar produced only with HCP or with RC. The compressive strength results suggest the existence of a secondary pozzolanic reaction when using HCP from a cement paste source, but such a pozzolanic reaction was fully perceived in XRD patterns when using concrete as parent material, unlike cement paste, possibly due to large crystalline sand peaks that could have hindered the effective identification of smaller crystalline peaks. [ABSTRACT FROM AUTHOR]

Marl soil is highly prone to erosion when exposed to water flow, posing a potential threat to structural stability. The common practice of stabilizing soil involves the addition of cement and lime. However, persistent reports of severe ruptures in many stabilized soils, even after extended periods, have raised concerns. In stabilized marls, unexpected ruptures primarily result from the formation of ettringite, which gradually damages the soil structure. This article aims to assess the impact of nanosilica on the formation of ettringite and the nanostructure of calcium silicate hydrate (C-S-H) during the marl soil stabilization process with lime. To achieve this, marl soil was stabilized with varying percentages of lime and nanosilica. X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images were collected to observe changes in mineralogy and microstructural properties. Various geotechnical parameters, including granularity, Atterberg limits, compressive strength, and pH, were measured. The results indicate that the uniform distribution of nanosilica in marl-lime soils enhances pozzolanic activities, calcium aluminate hydrate growth (C-A-H), and the nanostructure of calcium silicate hydrate (C-S-H). According to XRD and SEM experiments, the presence of nanosilica reduces the formation of ettringite. Moreover, the compressive strength of modified samples exhibited an upward trend. In the experimental sample manipulated with 1% nanosilica combined with 6% lime, the compressive strength increased by 1.84 MPa during the initial 7 days, representing an approximately 18-fold improvement compared to the control sample. [ABSTRACT FROM AUTHOR]

Particulate calcium oxide (CaO) has been successfully used for the control of sea urchin and starfish populations. Recent studies have proven its efficacy in killing planktonic copepods, making it a promising and cheap option for salmon louse control in the Atlantic salmon (Salmo salar) farming industry. Additionally, preliminary laboratory tests demonstrated that exposure to 0.2 g/L-0.6 g/L of fine CaO particles induced significant mortality of salmon louse (Lepeophtheirus salmonis) in the planktonic stages. The present study investigated the effects of water treatment with fine CaO particles [0.2 g/L or 127.4 g/m²; 0.1mm-0.3 mm], conducted twice a week for three consecutive weeks at 5℃ and 12℃ on Atlantic salmon post-smolt in a flow-through system. The study compared mortality rates and histopathology of skin, eyes, gills, and intestines between treated and untreated control salmon. The results indicated that CaO exposure did not induce fish mortality or histopathological damages in the skin, eyes, or intestines. Although there were no significant effects of CaO exposure on gill inflammation or hyperplasia, the exposure did increase the occurrence of gill vascular injuries and necrosis in small portions of the tissue (< 10% of the respiratory gill tissue in most of the samples) by 60% and 35%, respectively. The effect was not modulated by temperature or time. The results indicate that the CaO treatment protocol used in this study is not lethal to Atlantic salmon and is safe for most analyzed tissues. Nonetheless, the induction of vascular damage and necrosis in the gill, albeit in small tissue portions, emphasizes the need for further research. It is crucial to develop a protocol that avoids such lesions, ensuring the secure application of CaO as an antiparasitic treatment in salmon aquaculture. [ABSTRACT FROM AUTHOR]

Waste oyster shells were utilized to produce calcium carbonate (CaCO3) by grinding. This CaCO3 was then reacted with acetic acid to yield calcium acetate monohydrate (Ca(CH3COO)2·H2O). Both CaCO3 and Ca(CH3COO)2·H2O were used as precursors for synthesizing calcium oxide (CaO) through thermal decomposition at 900 °C and 750 °C, respectively. The yields of CaO from both precursors, determined through calcination experiments and thermogravimetric analysis (TGA), exceeded 100% due to the high purity of the raw agents and the formation of calcium hydroxide (Ca(OH)2). X-ray fluorescence (XRF) analysis revealed a CaO content of 87.8% for CaO-CC and 91.5% for CaO-CA, indicating the purity and contamination levels. X-ray diffraction (XRD) patterns confirmed the presence of CaO and minor peaks of Ca(OH)2, attributed to moisture adsorption. Fourier-transform infrared (FTIR) spectroscopy identified the vibrational characteristics of the Ca-O bond. Scanning electron microscopy (SEM) showed similar morphologies for both CaO-CC and CaO-CA, with CaO-CA displaying a significant amount of rod-like crystals. Based on these results, calcium acetate monohydrate (CA) is recommended as the superior precursor for synthesizing high-purity CaO, offering advantages for various applications. [ABSTRACT FROM AUTHOR]

This study investigated biodiesel production via the transesterification of grapeseed oil with plasma-modified biomass-based catalysts originating from starfish. Dried starfish was first converted into magnesium and calcium oxide through heat treatment and then further modified by plasma engineering to improve the catalyst's surface area and active sites via zinc addition. The Zn content was added via plasma engineering in the ratios of starfish (Mg0.1Ca0.9CO3): ZnO varying from 5:1, 10:1, to 20:1. The structure and morphology of the catalyst were confirmed through XRD, SEM, and XPS analysis. After the Zn addition and activation process, the surface area and the basicity of the synthesized catalysts were increased. The plasma-modified catalyst showed the highest basicity at the ratio of 10:1. Based on HPLC analyses, the optimized biodiesel yield in transesterification demonstrated 97.7% in fatty acid conversion, and its catalytic performance maintained 93.2% even after three repeated runs. [ABSTRACT FROM AUTHOR]

Ultra-High Performance Concrete (UHPC), with its excellent tensile properties, can be used as an alternative to decorative materials that are heavy in cross-section, enabling architectural decoration field to develop in the direction of light weight and changeable shape. However, the extremely low water-binder ratio of UHPC produces obvious autogenous shrinkage, which leads to the development of many micro-cracks. When the micro-cracks develop to a certain extent, they can have a very negative impact on the finishing of the architecture. This paper studies the influence of medium-burnt quicklime dosing on the hydration process and mechanical properties of UHPC cured at room temperature and elucidates the mechanism by which medium-burnt quicklime reduces autogenous shrinkage in UHPC. The results show that the crystal growth pressure generated by the hydration of f-CaO (free calcium oxide) can significantly compensate the autogenous shrinkage of UHPC. The dosage of 3 % medium-burnt quicklime can make the mechanical properties and shrinkage properties of UHPC reach the relative optimum, and the autogenous shrinkage of UHPC can be reduced to 181.36 με. Although the medium-burnt quicklime reduces the hydration products by delaying the hydration of UHPC, it also can reduce the porosity and the percentage of the multi-harmful pores, and refine the pore aperture. In addition, the interfacial transition zone between the UHPC matrix and the steel fibres can be reduced due to the extrusion of Ca(OH) 2 crystal growth pressure on the surrounding crystals, resulting in a tighter lapping between the crystals. [ABSTRACT FROM AUTHOR]

The University of Newcastle (UON) and Jord International Pty Ltd. (Jord) have jointly developed a novel concept for the storage of energy from renewable and fossil fuel sources. The process, referred to as the pressurized regenerative calcium cycle (PRC2), relies on cyclic carbonation and calcination of CaO/CaCO3, in which low-cost electrical energy (i.e., off-peak, or excess generation from renewables) drives the calcination reaction and electricity is generated as required through the carbonation reaction. Initial proof-of-concept testing of the process was previously conducted within an existing fluid bed reactor at UON. The PRC2 concept was successfully demonstrated by maintaining the fluid bed reactor at a constant temperature by using the heat released during the reaction of calcium oxide and carbon dioxide. Following proof-of-concept testing, further refinement of the PRC2 process, which is the subject of this paper, was conducted to address its shortcomings and, importantly, facilitate the detailed design, construction, and operation of a large-scale demonstration plant. Nine different configurations were examined for the PRC2 process, for each of which a combined experimental, process modelling, and techno-economic assessment was completed. Experimental investigations were conducted to determine the suitability of carbonate materials for the PRC2 process. Process modelling and levelized cost of storage (LCOS) calculations were concurrently conducted and revealed that the molten salt approach (Option 9) was the most promising, having superior round-trip efficiency and lowest LCOS. For practical reasons (e.g., technical difficulties of working with molten salts), Option 3 (indirect power generation using a fluid bed reactor) was deemed the most feasible option for a demonstration scale plant. The LCOS for Option 3 (assuming a 100 MWe capacity) was calculated to be AUD 245 per MWh, which is on par with the cost of batteries for peak power replacement applications (the cost associated with lithium-ion batteries is AUD 370 per MWh). [ABSTRACT FROM AUTHOR]

The Church of Panaghia Krena is a very important Byzantine monument situated in the island of Chios, well-known due to the high aesthetic value of the ceramic tile decoration on its facades and of its frescoes. The church suffered severe damage especially due to the 1881 devastating Chios earthquake and different interventions were implemented soon after (1884), consisting mainly of the reconstruction of collapsed areas and the addition of ties. Nevertheless, deterioration of old damages and appearance of new ones was observed. Thus, a restoration program was carried out between 2000 and 2007. This paper presents the basic characteristics of all types of historic materials examined, the main results of the in situ and laboratory experimental program carried out for the selection of the raw materials, and the design of optimum compositions of mortars and grouts to be used for the restoration works. The importance of in situ pilot applications is underlined, as well as of the production of site-specific aggregates for the repointing mortars by crushing a local rock, in order to succeed the adequate reddish color to match with the original mortars and bricks still preserved and achieve an aesthetic harmony with the color hue and texture of the original materials. [ABSTRACT FROM AUTHOR]

The construction and maintenance of road infrastructure is required for the sustained economic growth of communities and societies. Nonetheless, these activities imply the tangible risk of boosting the depletion of non-renewable resources (e.g., aggregates and binders). A widely used strategy for preserving as much of these natural resources as possible is the design of high-performance composite materials. For instance, antistripping agents (ASAs) are employed to mitigate the loss of adhesive bonding between asphalt binders and aggregates, enhancing the mechanical behaviour of hot-mix asphalts (HMAs). There is still no consensus on the effectiveness of ASAs. In this regard, the present research aims to contribute to the literature by conducting a case study on the influence of three different ASAs (hydrated lime, an amines-based liquid additive, and a silanes-based liquid additive) on the moisture susceptibility, stiffness, and rutting resistance of HMA. For these purposes, indirect tensile strength, indirect tensile stiffness modulus, and uniaxial cyclic compression tests were carried out. Overall, the involved experimental protocol drew the main conclusion that the incorporation of hydrated lime as a mineral filler (at a content of 1.68% by dry weight of aggregates) is capable of improving the mechanical performance of HMAs through decreases in humidity sensitivity and permanent deformation, together with a slight increase in rigidity. [ABSTRACT FROM AUTHOR]

Due to its acidic nature and high fluoride concentration, hydrated lime (Ca(OH)2) is commonly used for neutralization and fluoride control in semiconductor wastewater treatment. This study investigated the efficacy of treating high fluoride-containing wastewater using hydrated lime derived from oyster shells as an alternative to limestone. Overall, the characteristics of removing pollutants in acidic wastewater using shell-based hydrated lime showed similar patterns to hydrated lime from limestone. The treatment efficiency was 50% or less under theoretical Ca/F molar ratio (=0.5) conditions for the formation of fluorite (CaF2), while the fluorine removal rate reached 99% under somewhat higher Ca/F conditions due to the influence of ionic components in the wastewater. Interestingly, chloride content did not increase even in the initial reaction stages, in contrast to our concerns about oyster shells generally containing salt to a certain extent due to their growth in seawater; instead, the chloride concentration decreased over time, similar to nitrate (NO3−). In controlling fluoride in wastewater, surpassing the theoretical Ca/F molar ratio, particularly considering the presence of other anionic species such as SO4²− and PO4³−, the optimal Ca/F ratio for fluoride removal was found to be 1.59. This value is approximately 16% lower than the calculated value (Ca/F = 1.85) when accounting for other anions. X-ray diffraction results confirmed the presence of CaSO4, Ca3(PO4)2, and CaF2 in the precipitate recovered after the reaction, indicating the effective removal of ionic contaminants. This observation suggests that oyster shell-derived hydrated lime could serve as a viable calcium resource for treating acidic wastewater and represents a potential alternative to traditional limestone-based methods. [ABSTRACT FROM AUTHOR]

By using tartaric acid (TA) as a wet‐method modifier to modify steel slag powder (SS), it is helpful to reduce the content of free calcium oxide (f‐CaO) in SS and further improve the mechanical properties and soundness of SS as supplementing cementitious materials (SCM) in the mortar. The results indicate that with the addition of 2 wt% of TA, the number of large particles bigger than 45 µm in the SS decreased, resulting in predominantly smaller particles smaller than 45 µm. While the specific surface area increased from 417 to 704 m2/kg, the water consumption at standard consistency was significantly reduced. The soundness of the paste SS as SCM had improved including the f‐CaO content decreased from 4.81% to 0.95%, and the Le Chatelier expansion reduced from 4.5 to 1.5 mm. The mechanical properties were significantly enhanced, with the flexural strength increasing from 5.6 to 7.8 MPa, and the compressive strength rising from 38.8 to 52.7 MPa. After 28 days of curing in water, the hydration products of the mortar are hydrated calcium silicate (C‐S‐H), calcium hydroxide (CH), and calcium carbonate (CaCO3). [ABSTRACT FROM AUTHOR]

The physicochemical properties of steel slag were investigated using SEM and IR, and it was found that free calcium oxide and free magnesium oxide in steel slag produce calcium hydroxide when in contact with water, leading to volume expansion. Thus, the expansion rate of steel slag itself was first investigated, and it was found that the volume expansion of steel slag was more obvious in seven days after water immersion. Then, the cement dosages of 5% and 6% of the steel slag expansion rate and cement-stabilized gravel volume changes between the intrinsic link were further explored after the study found that the cement bonding effect can be partially inhibited due to the volume of expansion caused by the steel slag, so it can be seen that increasing the dosage of cement can reduce the volume expansion of steel slag cement-stabilized gravel with the same dosage of steel slag. Finally, a prediction model of the expansion rate of steel slag cement-stabilized gravel based on the BP (back propagation) neural network was established, which was verified to be a reliable basis for predicting the expansion rate of steel slag cement-stabilized aggregates and improving the accuracy of the proportioning design. [ABSTRACT FROM AUTHOR]