Subsequent Hydration Research Articles

Side reaction in the hydrogen and carbothermal reductions of BaO and BaCO3: The role of an infinitesimal amount of water

Alkaline earth (AE) metals are irreplaceable ingredients in the synthesis of AE metal-based antiperovskite oxides, and it can be achieved by a chemical reduction of a stable AE metal compound. In this study, hydrogen and carbothermal reduction of BaO and BaCO3 were attempted, and we here report an undesirable side reaction creating barium hydroxide (Ba(OH)2) as the product of the reaction with the small amount of water in ultra-high purity inert gas used in the reduction processes. Such side reaction pathways and products are hardly identifiable in a high-temperature reaction; yet, systematic investigations on phase evolutions using X-ray diffraction, IR spectroscopy, and thermogravimetric analysis enabled the detection of Ba(OH)2·xH2O. Unintentional creation of alkaline earth metal oxides in intermediate and subsequent hydration even under a negligible amount of H2O may lead to an unexpected loss of alkaline earth metal element and, consequently, its deficiency in a desired final product.

Effects of accelerated carbonation and high temperatures exposure on the properties of EAFS and BOFS pressed blocks

The accelerated carbonation of steel slag can improve its subsequent application as construction materials and can also store CO2 as stable minerals. Due to the differences in the production process, electric arc furnace slag (EAFS) and basic oxygen furnace slag (BOFS) acquire diverse physical and chemical properties, which expected to perform differently upon accelerated carbonation. Especially considering the potential use as green building material, thereby may be subject to fire risk. This research aims at comparing the influence of carbonation temperature, CO2 pressure, and carbonation time on mechanical properties and carbonation efficiencies of EAFS and BOFS pressed blocks, and emphasizing on their performances under elevated high temperatures. Results show that BOFS block has a much better performance than EAFS block, with about twice the compressive strength and CO2 uptake, owing to the higher calcium content and more reactive calcium mineral (portlandite) existed. The strengths of both two types of steel slag pressed blocks were found to increase with the increase of high temperature exposure up to 400 °C due to subsequent hydration reaction induced by elevated temperature. Although a slight decrease of compressive strength can be found after further heating at 600 °C, the residual strength was still comparably higher than that at 20 °C. However, with further increase of heating temperature up to 800 °C, a significant reduction in strength was noticed for both EAFS and BOFS blocks, associated to the decomposition of carbonates phases as the main contributor of bearing-strength within the blocks.

Whey beverage improves hydrating capacity of the soccer players

The hydration process is critical in soccer players. The hydrating capacity, energy recovery, and electrolyte excretion in urine were determined by the use of a whey beverage as a hydration medium for high-performance athletes compared to the effects of purified water and a sport beverage. The study was carried out through an approved research protocol, which contemplates the determination of hydrating capacity by monitoring body weight during a period of exercise and a subsequent hydration period. Energy recovery was determined by monitoring blood glucose levels and electrolyte excretion was performed by quantifying the concentration of sodium (Na+ ), potassium (K+ ), calcium (Ca2+) and magnesium (Mg2+) in urine samples provided by the participants during the research protocol. It was concluded that the whey beverage has an appropriate capacity for hydration and energy recovery, while with regard to minerals it was observed that it effectively regulates the excretion of Na+ , Ca2+ and Mg2+ .

Microstructure of Portland cement paste subjected to different CO2 concentrations and further water curing

Understanding the effect of formed calcium carbonate and highly polymerization of silicates on the microstructure of cement paste exposed to early CO2 curing and further hydration process is crucial to comprehend the mechanisms of CO2 curing. In this paper, the cement pastes were further cured in water after CO2 curing under two CO2 concentrations (3% and 20%) and the carbonation depth, compressive strength, composition and morphology of the formed products were characterized. The results showed that calcite was the main product generated in CO2-cured pastes and its content was increased with the increasing CO2 concentration. The formed calcium carbonate provided additional nucleation sites and accelerated the hydration of C3S in further water curing. Furthermore, calcium carbonate was consumed by C3A to form calcium aluminate monocarbonate, which delayed the transformation of ettringite to monosulfate during further water curing. The decarbonation temperature of the formed calcium carbonate was increased with the increase of the CO2 concentration, but it was decreased in further water curing due to participating the further hydration process. The early carbonation curing improved the polymerization of silica gel, which was decreased in the subsequent hydration due to the formation of C-S-H. The CO2-cured sample showed higher early compressive strength and comparable long-term compressive strength compared to the conventional samples due to the lower porosity.

Anisotropy-revealed change in hydration along the Alaska subduction zone

AbstractMegathrust earthquake behavior in subduction zones is controlled by a variety of factors including the hydration state of the subducting slab. Increased hydration reduces the occur-rence of great, damaging earthquakes by diminishing the strength of the material along the interface between tectonic plates. Understanding variations in hydration in subductions zones is necessary for properly assessing the overall hazard posed by each region. Fortunately, seismic anisotropy is strongly dependent upon hydration of the subducting crust and litho-sphere. I present shear-wave splitting measurements that illuminate changes in anisotropy, and therefore hydration, of the subducting Pacific plate beneath the Alaska subduction zone (northern Pacific Ocean). Variations in shear-wave splitting directly correlate to changes in the behavior of great, megathrust earthquakes. My measurements show that the Shumagin seismic gap is characterized by a hydrated subducting slab, explaining the long-term lack of great earthquakes. Observations in the immediately adjacent Semidi segment, which experiences great events regularly, indicate a far less hydrated slab. These results are driven by the preferential alignment of paleo-spreading fabrics of the Pacific plate. Where fabrics are more closely aligned with the orientation of the trench, outer-rise faulting and plate hydration is enhanced. These results highlight the importance of changes in preexisting slab structures and subsequent hydration in the production of great, damaging earthquakes.

Microstructure of cement paste subject to ambient pressure carbonation curing

This study investigated the microstructure of ordinary Portland cement paste subject to early age ambient pressure carbonation curing in a flexible enclosure. The high-pressure carbonation at 5 bar and the normal hydration were used as references. Both ambient-pressure and high-pressure carbonation was carried out with pure gas (99.9% CO2) for 12 h. It was found that ambient pressure carbonation could achieve comparable carbon uptake and strength gain as high pressure at both early and late age. Nevertheless, ambient carbonation was more economic and practical for precast products of different sizes and shapes. In order to examine this mechanism, X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), 29Si nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and nitrogen adsorption/desorption (NAD) were adopted to characterize the microstructural development after early carbonation curing under both ambient pressure and high pressure. Ambient pressure carbonation reaction took place more on the surface than in the core due to the limited CO2 diffusion so that the surface layer was more densified. The NAD results showed that ambient pressure performed better than high pressure in terms of reducing the cumulative pore volume and refining the capillary pore size. Ambient pressure could produce well crystalline carbonates as high pressure as deduced by XRD, TGA, FTIR and SEM images. The generation of calcium carbonate and its intermingling effect with hydration products were the main reasons for the strength gain and microstructural development of paste after early carbonation. Besides, SEM images showed that ambient pressure tended to produce calcium carbonates along the surface of C-S-H filling pore structure. As subsequent hydration proceeded, the increase of well crystalline carbonates was seen more in ambient pressure carbonation than high pressure based on TGA. NMR revealed that ambient pressure could enhance the polymerization of silicon in C-S-H promoting the early strength gain and maintain high Ca/Si ratio.

Structural Transitions During Formation and Rehydration of Proton Conducting Polymeric Membranes.

Knowledge of the transitions occurring during the formation of ion-conducting polymer films and membranes is crucial to optimize material performances. The use of non-destructive scattering techniques that offer high spatio-temporal resolution is essential to investigating such structural transitions, especially when combined with complementary techniques probing at different time and spatial scales. Here, a simultaneous multi-technique study is performed on the membrane formation mechanism and the subsequent hydration of two ion-conducting polymers, the well-known commercial Nafion and a synthesized sulfonated poly(phenylene sulfide sulfone) (sPSS). The X-ray data distinguish the multi-stage processes occurring during drying. A sol-gel-membrane transition sequence is observed for both polymers. However, while Nafion membrane evolves from a micellar solution through the formation of a phase-separated gel, forming an oriented supported membrane, sPSS membrane evolves from a solution of dispersed polyelectrolyte chains via formation of an inhomogeneous gel, showing assembly and ionic phase separation only at the end of the drying process. Impedance spectroscopy data confirm the occurrence of the sol-gel transitions, while gel-membrane transitions are detected by optical reflectance data. The simultaneous multi-technique approach presented here can connect the nanoscale to the macroscopic behavior, unraveling information essential to optimize membrane formation of different ion-conducting polymers.

Soluble Salts Quantitative Characterization and Thermodynamic Modeling on Roman Bricks to Assess the Origin of Their Formation.

The environmental weathering and the formation of efflorescences on the brick walls are studied at the “Casa di Diana” Mithraeum at Ostia Antica archaeological site. Previous studies on subsoil, bedrock, hydrological systems and environmental conditions, and new ion chromatography analysis combined with ECOS-RUNSALT and Medusa-Hydra thermodynamic modelling software, had allowed us to identify the subsoil contamination related to soluble salts. The atmospheric acidic gases, CO2 and SO2, are determined as the main salt weathering species. A dry deposition after a subsequent hydration action from the shallow freshwater aquifer that reaches up to 1 m on the walls is identified as the mechanism of salt formation. An evaluation of potential sources such as the nearby Fiumicino airport, CO2-rich gases inputs from fumaroles and CO2 inputs was also debated. The risk level of contamination the surfaces of the materials should be considered mildly/very polluted with a medium/high risk of hygroscopic moisture due to the high concentration of sulphates.

Equine cervical remodeling during placentitis and the prepartum period: a transcriptomic approach

Cervical remodeling is a critical component in both term and preterm labor in eutherian mammals. However, the molecular mechanisms underlying cervical remodeling remain poorly understood in the mare. The current study compared the transcriptome of the equine cervix (cervical mucosa (CM) and stroma (CS)) during placentitis (placentitis group, n = 5) and normal prepartum mares (prepartum group, n = 3) to normal pregnant mares (control group, n = 4). Transcriptome analysis identified differentially expressed genes (DEGs) during placentitis (5310 in CM and 907 in CS) and during the normal prepartum period (189 in CM and 78 in CS). Our study revealed that cervical remodeling during placentitis was dominated by inflammatory signaling as reflected by the overrepresented toll-like receptor signaling, interleukin signaling, T cell activation, and B cell activation pathways. These pathways were accompanied by upregulation of several proteases, including matrix metalloproteinases (MMP1, MMP2, and MMP9), cathepsins (CTSB, CTSC, and CTSD) and a disintegrin and metalloproteinase with thrombospondin type 1 motifs (ADAMTS1, ADAMTS4, and ADAMTS5), which are crucial for degradation of cervical collagens during remodeling. Cervical remodeling during placentitis was also associated with upregulation of water channel-related transcripts (AQP9 and RLN), angiogenesis-related transcripts (NOS3, ENG1, THBS1, and RAC2), and aggrecan (ACAN), a hydrophilic glucosaminoglycan, with subsequent cervical hydration. The normal prepartum cervix was associated with upregulation of ADAMTS1, ADAMTS4, NOS3 and THBS1, which might reflect an early stage of cervical remodeling taking place in preparation for labor. In conclusion, our findings revealed the possible key regulators and mechanisms underlying equine cervical remodeling during placentitis and the normal prepartum period.

Effects of polycarboxylate ether (PCE)-based superplasticizer on the dissolution and subsequent hydration of calcium oxide (CaO)

Calcium oxide (CaO) is an important construction material, used as expansive agent, alkaline activator, and repairing material for historical structures. In this study, the dissolution and subsequent hydration of CaO, with or without the polycarboxylate ether (PCE)-based superplasticizer, were investigated to elucidate the complex crystallization process of calcium hydroxide (Ca(OH)2). On contact with pure water, CaO particles began to hydrate within a few minutes, while releasing a significant amount of heat. Adding superplasticizer slowed such rapid heat evolution by forming a dormant period and significantly affected the crystallinity of the hydration product. The dormant period was controllable by the amount of added superplasticizer. Moreover, as a result of early nucleation of Ca(OH)2, the formation of 10–100-nm spherical nanoparticles was observed via an in-situ transmission electron microscope, which completely differed from the final crystal shape of the hydration product.

Analysis of alkali leaching mechanism on as-built cement concrete bridge deck pavement

A new distress type, namely alkali leaching, was recently observed to have developed on an as-built dense-graded asphalt concrete (DGAC) paved on a cement concrete bridge deck in China. Not only does alkali leaching affect the aesthetic appearance of the cement concrete bridge deck pavement (CCBDP) due to the distinctive color contrast, it also creates a potential threat to the service life of the bridge. In this paper, an alkali leaching distressed section of a CCBDP in Shaanxi Province (China) was studied. The study results indicated that whitish spots cannot be removed by natural water. In situ pH measurements indicated highly alkalinine materials appear on the surface of pavement layers. Based on these findings, the formation mechanism of alkali leaching on CCBDP was analyzed. The corresponding results showed that the main mineral of alkali leaching was Calcium Carbonate (CaCO3). Under wet conditions, rainwater infiltrates into the cement bridge deck from the sides of the pavement. Continuous exposure to moisture or humid environments facilitates the subsequent hydration to generate Ca(OH)2, which is the alkaline source for alkali leaching. The generated Ca(OH)2 migrates with rainwater to the pavement surface through capillary action. With the repeated circles of wet and dry conditions, the in-situ carbonation products lead to formation of alkali leaching on the pavement surface.

De novo synthesis of an l-lemonose thioglycoside donor from d-Threonine

A short de novo synthesis of an l-lemonose thioglycoside donor is described starting from d-threonine. The synthesis leverages a Dieckmann condensation and Stork-Danheiser transposition to arrive at a key vinylogous ester intermediate on gram scale. Ensuing 1,2-addition diastereoselectively establishes the C3 tetra-substituted center and subsequent glycal hydration allows for anomeric functionalization to the thioglycoside. 1H and NOESY NMR analyses reveal that the major α-anomer of the thioglycoside deviates from the expected 1C4 conformation.

Study of adhesion properties and mechanism of sodium silicate binder reinforced with silicate fume

In this study, the effect of different amounts of silica fume additive on the bonding strength of sodium silicate binder, over time, was studied. It has been concluded that silica fume can improve the bonding strength and humidity resistance of sodium silicate bonded sand. The microscopic morphology of the adhesive film was examined by scanning electron microscopy, and the functional group changes of the polymerised adhesive were analysed by Fourier-transform infrared (FT-IR) spectroscopy. In addition, the hardening mechanism, between the sodium silicate binder and silica fume on the sand surface, and the hydration reaction mechanism, after polymerisation, were investigated using first-principles calculations in the CASTEP program based on density functional theory (DFT). It was found that silica fume enhances the binding energy of the binder by enhancing the degree of polymerisation, while subsequent hydration of the hardened binder is a spontaneous reaction. After the sodium silicate binder hardens, the water molecules are adsorbed by unpolymerised –OH and Na+; these water molecules destroy the -Si-O-Si bonds to depolymerise the sodium silicate bonded network. This research provides important theoretical support for improving or even eliminating the hygroscopic properties of sodium-silicate-bonded sand during casting.

Performance of eco-concrete made from waste-derived eco-cement

Abstract In this study, an eco-cement was synthesized primarily from municipal solid waste incineration (MSWI) residues and appraised as a stand-alone binder in concrete. In addition to thorough laboratory testing, appraisal was extended to a pilot trial involving full-scale masonry unit production. The raw feed of the contrived eco-cement was supplemented by fractional additions of calcium hydroxide (6 wt %) and sintered at a clinkering temperature of 1100 °C. The resulting clinker (eco-cement) demonstrated latent hydraulicity when reacted with water and strong carbonation reactivity when reacted with carbon dioxide. Carbonation curing was found to both increase and accelerate strength-yield – achieving almost 1.5 times the ultimate 90-day hydraulic strength in just one day – without compromising additional latent strength gains from subsequent hydration. The binder performance was benched against control specimens prepared from ordinary Portland cement (OPC). The study’s final “eco-concrete” was activated by carbonation for early strength and further hydrated for latent strength. Eco-concrete demonstrated improved durability over conventional concrete according to surface resistivity, freeze-thaw, and drying-shrinkage evaluations. Moreover, leaching results for commonly regulated heavy metals and chlorine confirmed the environmental stability of eco-concrete according to the adopted standard testing protocol. Finally, the field pilot demonstrably validated eco-concrete’s suitability as a commercial product, where manufactured full-size concrete masonry units (CMUs) met all physical and performance requirements of CSA-A165 and ASTM-C90 standards. The synthesis of eco-cement, and its use as a carbon-sequestering alternative binder in eco-concrete, holds reasonable merit for consideration as an adaptable cleaner production to improve current-day MSW incineration practice.

Preparation of Giant Polymersomes via Inkjet Printing and Confined Geometry Hydration Applied to Micropipette Aspiration Experiments

AbstractA novel facile approach to creating many localized giant polymersomes (GPs) (vesicles) is developed. This method allows for the easy capture and testing of the bulk properties of the GPs. Inkjet printing is shown to produce vesicles of a non‐ionic block copolymer, poly(ethylene oxide)16‐poly(butylene oxide)22 (E16B22). The printer deposits a polymer solution (i.e., water/glucose/polymer) on a hydrophobic glass slide. Upon drying, glucose is left between polymer lamellar. Subsequent hydration of the sample dissolves glucose, and as a result, a concentration gradient is generated, which provides the energy necessary for separating the neutral polymer layers. After about 2 h in water, GPs are observed and are free of organic solvents. This novel methodology provides for the efficient formation of localized GPs. The distribution of the solution allows for a metered approach to releasing the GPs. This combination facilitates the collection of vesicles for micropipette aspiration experiments.

Calcium-silicate-hydrate seeds as an accelerator for saving energy in cold weather concreting

Cold weather concreting is well-known for its high energy consumption and carbon emissions because it needs to take various measurements to prevent the frost damage of concrete. Effectively promoting the strength of concrete developed rapidly in cold weather is a crucial way to solve this problem. In this study, the chloride-free and green calcium-silicate-hydrate (C-S-H) seeds were used to modify the performance of Portland cement (PC) at the negative temperature. The results showed that the strength of PC adjusted by C-S-H seeds developed rapidly at negative temperature (−5 °C) within 28 d after several hours pre-curing; its strength value at 28 d (74.2 MPa) was comparable with that of PC cured at room temperature for 28 d (75.3 MPa). The addition of C-S-H seeds significantly accelerated the early hydration of PC during pre-curing and the subsequent hydration at negative temperature. The freezing point and the frozen water of cement paste were significantly reduced by C-S-H seeds and pre-curing, which can help to prevent the cement matrix from frost damage at −5 °C. This advantage was further demonstrated by the improvement of the microstructure caused by ice. The easy-operate and green method can significantly decrease energy consumption and CO2 emissions in cold weather concreting.

Reversely zoned plagioclase in lower crustal meta-anorthosites: An indicator of multistage fracturing and metamorphism in the lower crust

AbstractThis paper describes the formation mechanism of reversely zoned plagioclase, which has been observed frequently in lower crustal shear zones and is indicative of multistage fracturing and meta-morphism in the lower crust, by studying the microstructural and chemical characteristics of plagioclase in sparsely fractured anorthosites and anorthositic mylonites from the Eidsfjord shear zone, Langøya, northern Norway. Based on the field relationship between sparsely fractured anorthosite and anorthositic mylonite, the fracturing of anorthosite occurred before the formation of mylonite. In sparsely fractured anorthosites, transgranular fractures are observed; hydration-reaction products, including Na-rich plagioclase, occur within cracks and fractures, suggesting that hydration reactions occurred during or after fracturing. The hydration reactions in sparsely fractured anorthosites are estimated to have occurred at higher-pressure (P) amphibolite-facies conditions (~0.9–1.0 GPa and ~550–700 °C). In anorthositic mylonites, which are considered to have initiated by fracturing and subsequent hydration metamorphism at lower-P amphibolite-facies conditions (~0.7 GPa and ~600 °C), recrystallized plagioclase grains often show compositional zoning with an Na-rich core and a Ca-rich rim. Because the compositions of metamorphic plagioclase grains in the sparsely fractured anorthosites and those of the Na-rich cores of the reversely zoned plagioclase in anorthositic mylonites are similar to each other, the Na-rich cores of the matrix plagioclase in the anorthositic mylonites have recrystallized under higher-P amphibolite-facies conditions and then been overgrown or replaced by the Ca-rich rims under lower-P conditions. Consequently, the reversely zoned plagioclase observed frequently in lower crustal shear zones is an indicator of multistage brittle fracturing and subsequent hydration metamorphism during exhumation, providing information relevant to understanding the deep rupture process caused by repeated seismicity alternating with aseismic creep below the seismogenic zone.

Effects of dehydration and subsequent hydration stress on the cerebral neurosecretory cells of Eudrilus eugeniae (Kinberg, 1867)

Moisture is a limiting factor for the survival and distribution of earthworms. During rainy season earthworms come out from their water-filled burrows and during summer move deeper into the soil to prevent acute desiccational water loss. Moisture loving worms like Eudrilus eugeniae when subjected to the dry soil and then subsequently hydrated, both the types of neurosecretory cells (A and B cells) show contrasting neurosecretory changes. During dehydration stress (2, 4 & 6 hours), both A and B cells deplete, lose their cellular conformity with extensive vacuolation. But in subsequent hydration of desiccated worms for 4 hrs, there is accumulation of neurosecretory materials in both types of cells, chiefly in A cells. The result indicates involvement of both A and B neurosecretory cells during osmotic stress from the perspective of histomorphic variations and secretory dynamics.

Effects of dehydration and subsequent hydration stress on the cerebral neurosecretory cells of Eudrilus eugeniae (Kinberg, 1867)

Effects of dehydration and subsequent hydration stress on the cerebral neurosecretory cells of Eudrilus eugeniae (Kinberg, 1867)

Architecture of Hydrated Multilayer Poly(methacrylic acid) Hydrogels: The Effect of Solution pH

We report on the evolution of the internal structure of dry and hydrated poly(methacrylic acid) (PMAA) hydrogels by quantifying the extent of layer interdiffusion in hydrogen-bonded (HB) films and upon subsequent cross-linking and hydration. These hydrogels are produced by ethylenediamine (EDA)-assisted cross-linking of PMAA in spin-assisted (SA) and dipped HB PMAA/poly(N-vinylpyrrolidone) (PVPON) multilayers followed by complete release of PVPON at pH 8 due to severing of hydrogen bonds with the PMAA network. Internal hydrogel architecture was monitored by neutron reflectometry using deuterated dPMAA marker layers. We found that even in the highly stratified SA HB films, layer interdiffusion extends over three (PMAA/PVPON) bilayers. Cross-linking of this film induces marker layer interpenetration more deeply into the surrounding material, extending over five layers. The volume fraction of dPMAA at the nominal center of a marker layer decreased from 0.65 to 0.51 after cross-linking. Hydrated SA hydrogels preserve well-organized layering and exhibit a persistent differential swelling with two distinct swelling ratios corresponding to MAA cross-link-rich and cross-link-poor strata. In contrast, layer organization in dipped films decays rapidly with distance from the silicon substrate. Both types of hydrogel swelled by factors of two and four times their dry total thicknesses at pH 5 and 7, respectively, and exhibited elevated surface roughness upon hydration. To fit the neutron reflectometry data, a self-consistent model was developed wherein the amount of PMAA initially deposited was preserved through subsequent chemical modification and hydration. Our results open opportunities for the development of thin hydrogels with a regulated structure, which can be utilized for efficient sensing, protection, activation, and rapid response in an aqueous environment. The internal morphological hierarchy of these multilayer hydrogels affords a means of fine-tuning their response to pH, temperature, or light to a degree rarely possible for randomly cross-linked responsive networks or brushes.