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We focused on the efflorescence induced microstructural evolution of ettringite-rich systems prepared with calcium aluminate cement (CAC) and anhydrite. The effects of anhydrite on the visible efflorescence, and the corresponding capillary absorption of CAC-anhydrite mortars were revealed. The composition and microstructure of efflorescence-causing substances were investigated by optical microscope, in-situ Raman spectroscopy, scanning electron microscope, energy dispersive spectrometer, thermogravimetric analysis, and differential scanning calorimetry, at multi-scales. Results indicate that, besides the calcium carbonate, ettringite is another main component of efflorescence-causing substances. Compared with the neat CAC mortars, the addition of anhydrite has a significant effect on the degree of efflorescence by acting on the composition of hydration products and pore structure. In addition, methods are proposed for the prevention of efflorescence of CAC-anhydrite binary system. [ABSTRACT FROM AUTHOR]

The study investigates the drying behavior and desalination effectiveness of porous ceramic tiles made from fired clay materials like bricks or pottery on soil columns initially saturated with saline solution. Evaporation kinetics experiments compared the drying of saline soil with and without a ceramic tile. For soil without a ceramic cover, salt precipitation formed an efflorescent crust that initially (t ∼ 30 h) reduced the evaporation rate. However, with continued drying, the tensile stress caused cracks in the crust, allowing increased evaporation through the cracks (t > 200 h). When covered with a ceramic poultice, the saline solution was wicked into the porous ceramic by capillary action. Rapid salt efflorescence was observed on the ceramic surface. The ceramic layer initially reduced the soil evaporation rate due to pore clogging caused by salt precipitation. The pore structure characteristics of the ceramics significantly impacted their desalination performance. After an initial fast drying period controlled by evaporation, a reduced drying rate was observed as salt clogging effects became dominant, especially for the low porosity ceramic (t ∼20 h). The porous ceramic poultices could effectively extract salts from the soil, but their desalination efficiency depended critically on their pore structure properties. An industrial-based clay ceramic with large and more connected pores (porosity 0.33) was found to be around 62% more efficient in removing NaCl than a handmade pottery with small pores (porosity 0.18). [ABSTRACT FROM AUTHOR]

Dominant narratives of the Australian New Wave tend to frame the efflorescence of national filmmaking in the 1970s through the lens of Gough Whitlam's brand of cultural nationalism. The narrative usually runs as follows: state-funded films tended to favour a conservative, genteel and respectable aesthetic that came to be known as the "Australian Film Commission genre". This article uses Mark Fisher's concept of "popular modernism" to challenge this dominant account of the Australian New Wave first put forth by Susan Dermody and Elizabeth Jacka, outlining the ways in which social democracy and state funding provided the conditions that allowed filmmakers to produce radical films that were anti-nationalist in character. As we will argue, when national film production deviated from this configuration and became circumscribed by neoliberal restructuring and economic rationalism in the 1980s, the New Wave took on an increasingly nationalist impulse. The article will trace this trajectory through a narrative analysis of two films from lauded Australian director Peter Weir: The Cars That Ate Paris (1974) and Gallipoli (1981). [ABSTRACT FROM AUTHOR]

Geopolymer concretes are considered to be a potential sustainable, low-embodied carbon alternative for Ordinary Portland Cement (OPC) concrete. Alkali leaching is considered to be a major esthetic concern for Na-silicate-based geopolymers as it can lead to the formation of efflorescence products on the surfaces of concrete members exposed to humidity. In this context, this research aims to investigate the effect of the alkali content and the FA/GGBS mass ratio on the alkali leaching and formation of the efflorescence products. Paste cylinders were fabricated and cured in ambient conditions. Samples were submerged in deionized water and the concentration of the leached-out ions was measured. Efflorescence potential was also investigated by partial immersion of the samples in deionized water. The results highlight the complexity of the interacting parameters governing the formation of efflorescence products in geopolymer materials. Establishing relationships between the concrete mix variables and the risk of efflorescence seems unfeasible particularly because of the wide range of possible precursors and activators available to design geopolymer concrete mixes. To overcome this barrier, a practical performance-based testing method is developed. For the first time, by testing a wide range of geopolymer materials, performance-based requirements associated with the risk of efflorescence for geopolymer concrete surfaces exposed to humidity are calibrated. Four categories of risk are proposed and typical suitable exposure conditions for geopolymer concrete surfaces are suggested for each risk category. [ABSTRACT FROM AUTHOR]

Experimental investigations were conducted to assess the impact of factors such as relative humidity (RH%) and the H2O molarity of waterglass on the efflorescence behavior of geopolymer composites. Samples with sodium (Na) and potassium (K) bases were prepared, having varying waterglass molarities (M) (at 11 and 13 moles of water). These samples were categorized into three groups exposed to different average RH ranges: (i) 0%–70% RH, (ii) 70%–90% RH, and (iii) 90%–100% RH. This study analyzed the occurrence of efflorescence and its stability, employing analytical techniques such as x‐ray diffraction, scanning electron microscopy, and energy‐dispersive spectroscopy to examine the formation and characteristics of efflorescent deposits. Additionally, mechanical testing was conducted to evaluate the compressive and flexural strengths of the geopolymer samples, considering the impact of efflorescence on their durability. For instance, in the composite geopolymer specimen containing 11 M water, at a RH of 80%, the compressive strength is decreased by approximately 25% from 56.4 to 42.3 MPa. The findings revealed that when the RH falls within the 70%–90% range, a decrease in water molar content from 13 M to 11 M leads to a more pronounced occurrence of efflorescence when compared to other conditions. Efflorescence may also occur in different RH ranges and water molarities, but its occurrence is significantly lower compared to the 70%–90% RH and 11 M water. [ABSTRACT FROM AUTHOR]

The stabilization of recycled asphalt pavement (RAP) with alkali-activated cement (AAC) is a topic of growing interest for sustainable engineering, especially those containing alternative activators produced from waste. This study evaluated the effect of curing temperature on the stabilization of RAP with a metakaolin AAC and rice husk ash-derived activator for potential use in base and subbase layers in flexible pavement systems. Unconfined compressive strength (UCS), X-ray diffraction, and scanning electron microscopy tests were performed. Higher strength values were associated with higher temperatures and curing times. Curing oven time presented no influence over UCS and mineralogy. Blends cured at 20°C exhibited efflorescence formation and prolonged curing time at high temperatures negatively affected the mechanical performance. Curing temperature of 80°C up to 24 h promoted the formation and uniform distribution of cementing gels and a dense and compact structure, improving the compressive strength. [ABSTRACT FROM AUTHOR]

Visualization experiments with microfluidic pore networks are performed in this work to disclose interplay between salt precipitation, the corner liquid film flow, and gas–liquid displacement during evaporation. Two forms of salt precipitation are revealed: aggregated polycrystalline structures and large bulk crystals. It is found that gas bubbles can be formed because of imbibition of liquid into aggregated polycrystalline structures. The length of a corner liquid film can affect the direction of growth of the aggregated polycrystalline structures connected to the corner liquid film. Discontinuous corner liquid films can be transformed to continuous ones when they are touched by growing aggregated polycrystalline structures. The "sleeping" aggregated polycrystalline structures at the open surface of a microfluidic pore network, i.e., efflorescence, can grow again if they are touched by growing aggregated polycrystalline structures inside the microfluidic pore network, i.e., subflorescence. Because of efflorescence, the evaporation rate from a microfluidic pore network can increase first and then decrease. Moreover, a theoretical model is developed for the coupled transport of vapor diffusion in the gas zone and liquid flow as well as transport of dissolved salt in the corner liquid films in a capillary tube of square cross section so as to disclose the key parameters controlling the transport processes. [ABSTRACT FROM AUTHOR]

Hundreds of studies have been written in the last several decades on the advantages of using stone powder as a raw material in the production of fired clay bricks. The durability and long-term behavior of the finished product, however, have received very little attention in the literature. Clay bricks are generally fired at high temperatures in developing countries, which reduces the mechanical performance of the bricks. This is especially evident in extreme environmental settings where weathering leads to significant damage. The evaluation of concrete waste (stone powder) used to make fired clay bricks is the main topic of this study. There are two sections: the first evaluates how adding stone powder to clay bricks improves their physical characteristics such absorption, efflorescence, density, and firing shrinkage. The impact of stone powder on the mechanical characteristics of specimens of burned clay bricks, such as compressive and flexural strengths, is covered in the second section. The percentages of stone powder in the clay bricks are 0 %, 5 %, 10 %, 15 %, and 20%. While the ratio of dry soil to water content remains is 0.3. In this work three fire phases are used untel to the maximum temperature is reached. The first one is 300 °C, the second phase is 600 °C, and 900 °C for the third phase. The water absorption of specimens decreased as the quantity of stone powder increased, and efflorescence also decreased, according to the results for the physical attributes. The density does, however, somewhat rise with the amount of stone powder. Additionally, when the amount of stone powder was increased, the experimental results indicated that firing shrinkage decreased. Mechanically considered, clay brick specimens with 20% more stone powder showed stronger compressive flexural capabilities.

The different salt weathering issues of the sandstone in the Nankan Grotto have significantly influenced their preservation conditions. This work aimed to evaluate the petrography and environment constraints for salt weathering of three typical sandstones: yellow sandstone, cyan sandstone, and gray sandstone in the Nankan Grotto. Salt resistance test and acid leaching test were conducted on these three sandstones. In addition, the mineralogy, geochemical mass balance, micro-structure, and water transport properties of these sandstones were also analyzed. It is found that yellow sandstone had high quartz concentration, porosity, and water transport ability. Cyan sandstone had low calcite concentration, high porosity and medium water transport ability. Gray sandstone had high calcite concentration, low porosity and water transport ability. The decay of sandstones in the salt resistance test at 20 °C was faster than those at 5 °C and 35 °C. In addition, yellow sandstone was the most resistant to the salt resistance test, followed by cyan sandstone, and gray sandstone was the most vulnerable to the salt resistance test. In the H2SO4 acid leaching test, efflorescence pattern was the most likely type of decay in yellow and cyan sandstones. Thenardite was the exclusive salt in the yellow sandstone, while gypsum was the mainly salt in the cyan sandstone. Gypsum crust and subflorescence were the most common types of decay for gray sandstone. In the HNO3 acid leaching test, yellow and cyan sandstones did not show obvious variations. For gray sandstone, the secondary minerals were gypsum and dolomite, and crust pattern was observed. In general, the salt weathering of gray sandstone was more severe than yellow and cyan sandstones. The differences in petrography (mainly calcite concentration) and micro-structure of sandstone and the external environment leaded to the differences in the types, amounts, and locations of the salt crystallization in the acid leaching tests. These contributed to the different development of efflorescence, subflorescence, and crust patterns. Our research reveals the petrographic, micro-structural, and environmental constraints for different salt weathering processes of sandstones in the Nankan Grotto. [ABSTRACT FROM AUTHOR]

This research undertakes a comparative study between compacted phosphate-based (CPG) and alkaline-based (CAG) geopolymeric materials. The obtained materials underwent comprehensive evaluation through mechanical, physical, and chemical analyses. CPG exhibited superior mechanical strength, demonstrating an exponential growth with curing age in contrast to CAG. Both materials exhibited stable density over time, with CPG displaying a notably higher density attributed to its enhanced reactivity in an acidic medium. Dimensional variations revealed stable dimensions for CPG and subtle shrinkage for CAG, potentially associated with an observed efflorescence phenomenon. Visual assessments during water immersion highlighted the enhanced stability of CPG. Chemical analyses confirmed the persistence of mineralogical phases, such as quartz and illite, and the emergence of an amorphous geopolymeric network in both CPG and CAG samples. CPG materials featured aluminum phosphate phases, reinforcing structural integrity, while CAG materials exhibited sodium carbonate phases, introducing impurities, elucidating the superior performance of CPG over CAG. For the formation kinetics, CPG exhibited a faster reaction time than CAG, as evidenced by the evolution of pH, densification rate, and FTIR band over curing time. [ABSTRACT FROM AUTHOR]

Early childhood schoolbooks designed to teach children to read, have been shown not only to shape gendered identities in a limiting, binary format, but to lend the written word the appearance of unquestionable, and restrictive truth about the way the world is. Texts written for adults, too, may similarly limit what can be known, reining in the world's emergent efflorescence. Extending the concept of emergent listening, this paper develops the concept of emergent reading, a form of reading that is intimately and diffractively related to emergent listening and emergent writing. Emergent reading is relational, intra-acting with the emergent efflorescence of written words and with the materiality of the human and more-than-human world. [ABSTRACT FROM AUTHOR]

On the occasion of the reopening of the Dobrée Museum (Nantes, France), two statuettes of Egyptian origin, representing Harpocrate and Isis, were studied to shed light on the presence of the blue-green efflorescence on their surface. The efflorescence on the Harpocrate statuette was identified as being chalconatronite, while that which was present on the Isis statuette corresponded to sodium copper formate/acetate, probably due to the evolution of chalconatronite in an environment containing VOCs. The efflorescence appeared to be sensitive to the cyclic variation in relative humidity whereas it seemed stable. An experimental curative treatment to halt the reappearance was carried out. A series of pure water baths extracted a significant quantity of sodium. The treatment appeared effective and reduced the risk of a recrudescence of the efflorescence for both statuettes. However, when the efflorescence was dissolved on the Isis statuette, other compounds appeared to react with water, leading to acidification and a potential reaction with the lead in the alloy. A layer of lead carbonate/acetate on the surface appeared. The objects were then dried and protected with a highly concentrated acrylic varnish. They are currently being monitored to identify any new efflorescence that may appear during display. [ABSTRACT FROM AUTHOR]

The static compaction technique emphasizes the reduced activator dosage required to develop geopolymers. Therefore, it is crucial to comprehend the optimal alkaline activator concentration for blending low-calcium precursor (fly ash) with high-calcium precursor (GGBS) to produce geopolymer blocks. This work was designed to optimize structural blocks' compressive strength and durability. In experimentation, fly ash (FA) and slag (GGBS) proportions were initially investigated under NaOH solution with varying molarity (8–12) and curing conditions to develop a load-bearing structural block. Subsequently, the durability of the optimized block was evaluated over 56 days through subjection to sulfate and acidic solutions, with efflorescence monitored over the same period. The results reveal that the structural block comprised of 100% FA exhibits the highest compressive strength and lowest bulk density. Conversely, the block incorporating 25% slag that underwent hot curing demonstrates a remarkable 305% strength increase compared to ambient curing. Considering the physico-mechanical performance, the 100% FA block was chosen for durability investigation. The findings indicate a substantial strength loss exceeding 40% after exposure to sulfate and acidic environments over 56 days, coupled with pronounced efflorescence. Catastrophic failure occurs in all cases due to significant strength deterioration. The FTIR spectrum revealed the shifting of the wavenumber to a higher value and verified the depolymerization and leaching of alumina under acidic exposure. However, the developed geopolymer blocks demonstrate superior sustainability and feasibility compared to conventional fired clay bricks and cement-based FA bricks. Despite slightly higher costs, these blocks exhibit greater strength than their counterparts after enduring severe exposures. [ABSTRACT FROM AUTHOR]

What happens at the point of interchange between scholarly communities? We examine this question by investigating the case of growing ties between historical sociology and ethnography, two social scientific methods that once seemed to have little in common. Drawing on methodological writings by ethnographers and original interviews with practicing historical sociologists, we argue that these ties have been shaped by structural and methodological homologies between the two disciplines. Structurally, ethnography and historical sociology are similarly positioned in sociology more broadly, as enterprises with sometimes-tense relationships with dominant assumptions of the social sciences. Methodologically, both ethnographers and historical sociologists face the challenges of bounding the research process, navigating access to data, analyzing and retaining data while "in the field," and overcoming cultural distance between themselves and the worlds they are studying. Taken together, these findings extend work in the sociology of science and knowledge and suggest some key conditions for intellectual efflorescence. [ABSTRACT FROM AUTHOR]

One of the promising raw materials for the synthesis of geopolymers is perlite, which is a natural low-calcium aluminosilicate. This research studied the physical, mechanical and microstructural characteristics of perlite-based geopolymers modified with different mineral additives that were prepared using different methods of introducing the alkali components and curing conditions. The experimental results of the consolidated perlite-based geopolymer pastes showed that curing conditions and the method of introducing the alkali component into the geopolymer matrix had a minimal effect on the average density while demonstrating a significant boost in compressive strength. So, after thermal treatment, the compressive strength increased by 0.63 to 11.4 times for the mixes when fresh alkali solution was used and by 0.72 to 12.8 times for the mixes with the 24 h conditioned alkali solution. Maximum-strength spikes from 1.1 MPa to 13.2 MPa and from 0.7 MPa to 9.7 MPa were observed for the mixes with kaolin when prepared with fresh and conditioned alkali solutions, respectively. It was also observed that thermal treatment facilitates the compaction of the matrix structure by 18% and 1% for the non-modified mix and the mix modified with Portland cement. Perlite-based geopolymers modified with Portland cement and citrogypsum demonstrated a significant reduction in the initial and final setting times with both methods of introducing the alkali solution. On the surface of mixes modified with citrogypsum, regardless of the curing conditions and method of introducing the alkali component, an efflorescence substance was observed. The microstructural analysis of the consolidated geopolymer perlite-based pastes containing citrogypsum demonstrated a loose structure and the presence of efflorescence, which can be associated with a retardation in interaction processes between alkali cations and the aluminosilicate component. EDS analysis demonstrated that the presence of such elements as oxygen, sodium and sulfur may indicate the efflorescence of unreacted sodium hydroxide (NaOH), citrogypsum (CaSO4) and the products of their interaction in the form of crystalline hydrates of sodium sulfate (Na2SO4). [ABSTRACT FROM AUTHOR]

Salt efflorescence is one of the critical problems for the preservation of immovable silicate relics. Salt efflorescence mainly comes from continuous cycles of crystallization/dissolution or hydration/dehydration of salts in confined pores in silicate relics. Many protocols have been developed in attempts to alleviate possible salt damages with minor success because of endless water and salt feed from underground. In this study, we propose and design a novel technique for salt damage prevention and protection of immovable relics. Materials with higher water-absorbing ability than matrix are applied to control the water and salt migration direction in simulated sand samples. The distribution of moisture content on the surface of sand is followed by hyperspectral imaging. It appears that water and salt molecules will preferentially transport towards positions containing higher water-absorbing material. Both organic and inorganic high water-absorbing materials show effective in controlling the water and salt migration direction, which provides a new approach for the prevention and protection of salt efflorescence in silicate cultural relics. [ABSTRACT FROM AUTHOR]

ABSTRACT The composition of respiratory fluids influences the stability of viruses in exhaled aerosol particles and droplets, though the role of respiratory organics in modulating virus stability remains poorly understood. This study investigates the effect of organic compounds on the stability of influenza A virus (IAV) in deposited droplets. We compare the infectivity loss of IAV at different relative humidities (RHs) over the course of 1 h in 1-µL droplets consisting of phosphate-buffered saline (without organics), synthetic lung fluid, or nasal mucus (both containing organics). We show that IAV stability increases with increasing organic:salt ratios. Among the various organic species, proteins are identified as the most protective component, with smaller proteins stabilizing IAV more efficiently at the same mass concentration. Organics act by both increasing the efflorescence RH and shortening the drying period until efflorescence at a given RH. This research advances our mechanistic understanding of how organics stabilize exhaled viruses and thus influence their inactivation in respiratory droplets.IMPORTANCEThis study investigates how the composition of respiratory fluids affects the stability of viruses in exhaled droplets. Understanding virus stability in droplets is important as it impacts how viruses spread and how we can combat them. We focus on influenza A virus (IAV) and investigate how different organic compounds found in lung fluid and nasal mucus protect the virus from inactivation. We demonstrate that the ratio of organics to salt in the fluid is an indicator of IAV stability. Among organics, small proteins are particularly effective at protecting IAV. Their effect is in part explained by the proteins’ influence on the crystallization of salts in the droplets, thereby shielding the viruses from prolonged exposure to harmful salt concentrations. Understanding these mechanisms helps us grasp how viruses sustain their infectivity over time in respiratory droplets, contributing to efforts in controlling infectious diseases.

The surface spectral absorptivity of surface-whitened mortars due to the occurrence of efflorescence (i.e., mortars whose surface was covered with calcium carbonate) was measured, and the relationship between the spectral absorptivity and inspection capability of active thermography inspection was investigated. The spectral absorptivity of mortars increased significantly at a wavelength of approximately 3000 nm regardless of the presence/absence of the discoloration. Experiments for mortar specimens using optical lights with wavelengths in the visible, short wavelength, and medium/long wavelength ranges showed that the heating efficiency and defect detection capability of active thermography inspection were correlated with the surface spectral absorptivity, and were higher when long wavelength light was used as a heater. Defects in the surface-whitened mortar specimen were detected more efficiently when the specimen was heated using a CO2 laser, whose wavelength is in the long wavelength range, than when using an optical light having a wavelength in the visible/short wavelength range. [ABSTRACT FROM AUTHOR]

Concrete structures inevitably experience cracking, which is a common form of damage. If cracks are left undetected and allowed to worsen, catastrophic failures, with costly implications for human life and the economy, can occur. Traditional image processing techniques for crack detection and measurement have several limitations, which include complex parameter selection and restriction to measuring cracks in pixels, rather than more practical units of millimetres. This paper presents a three-stage approach that utilises deep learning and image processing for crack classification, segmentation and measurement. In the first two stages, custom CNN and U-Net models were employed for crack classification and segmentation. The final stage involved measuring crack width in millimetres by using a novel laser calibration method. The classification and segmentation models achieved 99.22% and 96.54% accuracy, respectively, while the mean absolute error observed for crack width measurement was 0.16 mm. The results demonstrate the adequacy of the developed crack detection and measurement method, and shows the developed deep learning and laser calibration method promotes safer, quicker inspections that are less prone to human error. The method's ability to measure cracks in millimetres provides a more insightful assessment of structural damage, which is, in comparison to traditional pixel-based measurement methods, a significant improvement for practical field applications. [ABSTRACT FROM AUTHOR]

The use of solid activators to prepare alkali-activated materials (AAM) holds great potential for on-site applications, as it eliminates the need to transport and store large quantities of concentrated alkaline solutions. This study compared the early-age properties and efflorescence between alkali-activated slag/fly ash (AASF) using solid and liquid sodium silicates as activators. The results revealed that AASF with solid sodium silicates exhibited comparable mechanical strength while possessing reduced initial setting time and flowability. All AASF mixtures were susceptible to efflorescence and carbonation, resulting in varying mineralogical compositions of carbonation products: Vaterite was detected in AASF with solid activators, while aragonite and pirssonite were identified in AASF with liquid activators containing 4 and 6 wt.% Na2O, respectively. The efflorescence of AASF exposed to bottom water was more severe than those exposed to natural conditions, as evidenced by the decalcification of reaction products, migration of alkalis, and formation of crystalline carbonates. [ABSTRACT FROM AUTHOR]

Moisture in historic built heritage is one of the main degenerative agents, because it supports or manifests itself through multiple pathologies. Current knowledge allows for the diagnosis and assessment of the problem, but there are deficiencies in the evaluation of corrective systems due to the time it takes for moisture to become significant. In response, this study proposes an experimental methodology that aims to reproduce the accelerated aging of real scale specimens under laboratory conditions. Thereby improving the understanding of the impact of moisture related deterioration on masonry structures. To achive this, eight masonry walls were constructed and subjected to eight cycles of sulfate crystallization. They were saturated with different sulfate concentrations (5% or 10%) and exposed to different drying conditions (outdoor or solar dehydrator) in order to identify the factors favoring sulfate crystallization and the resulting deterioration. The progress of the experiments was monitored using a hygrometer, a thermographic camera and photogrammetry. The results indicate that it is possible to induce efflorescence in real scale specimens. Temperature and moisture monitoring helped identify the solar dehydrator as a more effective drying treatment. While digital photogrammetry was considered inefficient for quantifying volumetric damage, since this technique can present errors greater than 2%, a value exceeding the observed wear. Reason why the weight of material detached at the end of the experiment was recorded and a positive correlation between the increase in sulfate concentration and the use of the dehydrator was observed. Finally, pertinent considerations are made to improve the experimental conditions. [ABSTRACT FROM AUTHOR]

Salt weathering is considered one of the most important factors leading to the damage of Petra's monuments. Inhabiting or limiting the crystallization of these salts could therefore prevent/slow down the destruction of Petra's sandstones. Using of sodium ferrocyanide as a salt crystallization inhibitor has been proved in the past as a prospective treatment measure against salt weathering. This study is the first to investigate the effectiveness of salt crystallization inhibitor on a stone material loaded with a salt mixture. The effect of sodium ferrocyanide on the crystallization of salt mixtures inside sandstone samples from Petra has been studied. The results showed that using of inhibitor changes the crystal morphology of salts from cubic to dendrites, which makes the drying time faster than that of pure salt solution. Therefore, allows the salt to crystallize on the surface of the stone in the form of harmless efflorescence rather than destructive sub-florescence. [ABSTRACT FROM AUTHOR]

Salt decay is one of the main decay mechanisms of the porous building materials but due to its complexity progress has been slow, both in terms of understanding the mechanism itself and defining mitigation solutions. Research has so far privileged a reductionist approach, focusing on the behavior of a few individual salts. However, the typical reality of these constructions is the presence of multi-ionic solutions from which, depending on the conditions, different types of salts can precipitate in different crystalline forms. The originality of Arnold and Zehnder was that they did not embrace reductionist approaches, maintaining the focus on salt mixtures and the way these behave in real constructions. This path has led to approaches to the problem and possible mitigation solutions that have not yet been adequately discussed and explored. In this review, I seek to identify the most interesting contributions of the two authors and the directions they suggest for future research. [ABSTRACT FROM AUTHOR]

Observing the efflorescence of scholarly and public discourse about memory and commemoration since about the 1970s, historians and others have expressed concerns about "the memory boom" and "the memory industry." Referring instead, and less negatively, to "the mnemonic turn," this article responds to those concerns. It shows that many critiques were based on a Manichean distinction between "history" and "memory"—and between "historiography" and "memory studies"—that led to faulty predictions about the future of scholarly and public interest in memory. It makes a strong case for a robust memory studies that seeks not to displace historical truth-telling but to work alongside it to understand when, where, and how historiography might or might not be an effective response to problematic memory politics and practices. [ABSTRACT FROM AUTHOR]

Salt flats are bare soil surfaces with elevated salinity levels which inhibit vegetation. They are commonly found in areas of coastal wetlands where salt in surface soil accumulates due to evaporation from the shallow saline water table. The expansion of these vegetation‐free zones may severely affect the bio‐ecological function of these coastal wetland systems. In this study, sand flume experiments and numerical modeling were carried out to investigate the mechanisms underpinning the development of salt flats in the elevated areas of coastal wetlands. We found that salt precipitation occurred on the soil surface where water content is low, but the hydraulic connection to the saline groundwater table is maintained. This connection is required for evaporation to promote upward porewater flow and bring salt to the surface. However, the surface salinity level decreases with increasing surface saturation due to the density‐driven removal of salt. As a result, salt efflorescence is absent on the surface with higher water saturations, despite strong evaporation. Density‐driven flows can be triggered by the evaporation‐induced upward salinity gradient and transfer salt from the surface back to the water table. Numerical simulations confirmed this salt removal process and suggested the intensity of the density‐driven flow is mainly dictated by the soil permeability in the unsaturated zone. The findings from this study increase understanding of the processes involved in the formation and evolution of salt flats. Key Points: Salt precipitated on the soil surface with continuous evaporation and low water saturationEvaporation‐induced upward salinity gradient can trigger salt fingersSalt fingers tended to form near the soil surface with higher water saturation and inhibited surface salt accumulation [ABSTRACT FROM AUTHOR]

Alternative materials need to be mapped, characterized, and valued in order to reduce clay usage. A study was conducted on the utilization of waste dolomite material from a mirror manufacturing factory in the production of bricks where the factory disposes 2500 tons of dolomite waste annually. Dolomite residue was mixed with clay raw material in various mass ratios of 90/10, 87.5/12.5, 85/15, and 82.5/17.5 wt%, extruded with proper moisture content, dried at 110 °C, and fired at 1000 °C and 1100 °C. The addition of dolomite resulted in an efflorescence on the surface of the bricks while also providing thermal insulation advantages and higher fire resistance. The addition of dolomite allowed for an increase in firing temperature to 1100 °C, which was initially not possible due to the melting characteristics of the clay. Dolomite also decreased the density of the bricks, which is crucial in order to decrease the dead load in structures. The produced bricks are intended for internal wall applications because of the efflorescence on the surface of the bricks. Overall, the addition of dolomite improved thermal conductivity and density, and other characteristics also showed suitable results. [ABSTRACT FROM AUTHOR]

In order to reduce the degree of efflorescence in alkali-activated metakaolin geopolymers, a modified 5A zeolite with cation-exchange properties was used to reduce the content of free alkali metal cations in the geopolymer. This work aims to investigate the effect of different dosages of modified 5A zeolite on the microstructure and properties of geopolymer by using compressive strength testing, pore structure analysis (BET), and SEM-EDS. The cation content in the leachate was evaluated using inductively coupled plasma atomic emission spectrometry (ICP-OES). The efflorescence area of the geopolymer was calculated using Image Pro Plus (IPP) software to evaluate the effect of modified 5A zeolite on the degree of efflorescence of the geopolymer and to reveal the effect of modified 5A zeolite on the migration patterns of Na+ and Ca2+ in the geopolymer. The results showed that modified 5A zeolite with a 4 wt.% content could optimize the pore structure and enhance the mechanical properties of MK geopolymer through internal curing and micro-aggregate effects, which could also exchange cations with the pore solution to form (N, C)-A-S-H gels. The Na+ leaching was reduced by 19.4%, and the efflorescence area of the MK geopolymer was reduced by 57.3%. [ABSTRACT FROM AUTHOR]

This paper characterizes the efficacy of borax on different properties of alkali-activated materials (AAMs). Fly ash (FA) and ground granulated blast slag (GGBS) were used as base substances at different ratios. The effects of borax on workability, compressive strength, efflorescence formation and crack resistance are the main ideas of the study. The results indicated the positive effects of borax on the properties of one-part fly ash/slag-based alkali-activated materials such as increasing workability and decreasing efflorescence. The microscopic images and scanning electron microscope (SEM) showed that the addition of borax reduced the cracks and a higher amount of slag made the samples denser with less unreacted raw materials, respectively. The compressive strength test results showed that borax had a detrimental impact at early ages with a positive effect at later ages. Binders with borax and 20-25% replacement of FA with GGBS were found to have the best performance when workability, compressive strength, efflorescence formation, and cracks on the samples were taken into account. [ABSTRACT FROM AUTHOR]

• Cement as a material used in the historical reconstructions of the Palace of Knossos. • Identification of the types of salts and crusts by WDXRF, XRD, FTIR and μ-Raman. • Formation of gypsum crusts and thenardite efflorescence resulting from the deterioration process of the cements. • Importance of material characterisation for the conservation of monuments. The Palace of Knossos, located on the island of Crete, Greece, is one of Europe's most important archaeological sites, serving as a testament to the Minoan civilization. Situated near the Mediterranean Sea, it is in close proximity to the seaport, airport, and industrial areas. Decay products commonly found in historical monuments within or near urban areas, such as black crusts and salt efflorescence, are also prevalent at the Palace of Knossos. To better understand the characteristics of the type of deterioration compounds found on cement in historical reconstruction zones, as well as their possible relationship with factors influencing the deterioration process, a multi-analytical approach was designed for the study of these materials. The results indicate that the black crusts primarily consist of gypsum and carbonaceous matter. However, the efflorescence salts are predominantly composed of thenardite instead of halite, despite the palace's proximity to the coastal area. These results may contribute to ongoing and future maintenance and preservation efforts for the monument. [ABSTRACT FROM AUTHOR]

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The present work addressed the study an episode of red waters of great extent, which was observed off the Oum Er Rbia estuary in spring 2019. The responsible species was Prorocentrum micans. The study was carried out on three stations with different characteristics, distributed in the estuary upstream and downstream of an urban wastewater discharge. The cell densities observed were maximum in March 2019. Some environmental parameters (temperature, salinity, dissolved oxygen, chlorophyll (a) and pheopigments) were simultaneously recorded. The P. micans densities increased from downstream to upstream with cell concentrations of 1.03c105 cell/l in S3, 9.1x106 cell/l in S2 and 14.11x107 cell/l in S1. The contribution of P. micans to the total dinoflagellates density was higher and reached 99.54% in station S1. These blooms would be associated with high concentrations of chlorophyll (a) and pheopigments, which equaled 40 µg/l and 909 µg/l, respectively, and dissolved oxygen supersaturations (17.05 mg/l). This phenomenon also corresponded to a marked decrease in salinity. According to the application of the Kruskal-Wallis test, the difference was found to be significant between the three stations (p = 0.0034). In addition, densities were higher in surface waters than in bottom waters at all three stations. However, this difference did not appear to be statistically significant (p > 0.05). [ABSTRACT FROM AUTHOR]

The present work addressed the study an episode of red waters of great extent, which was observed off the Oum Er Rbia estuary in spring 2019. The responsible species was Prorocentrum micans . The study was carried out on three stations with different characteristics, distributed in the estuary upstream and downstream of an urban wastewater discharge. The cell densities observed were maximum in March 2019. Some environmental parameters (temperature, salinity, dissolved oxygen, chlorophyll (a) and pheopigments) were simultaneously recorded. The P. micans densities increased from downstream to upstream with cell concentrations of 1.03×10^5 Cell/l in S3, 9.1×10^6 Cell/l in S2 and 14.11×10^7 Cell/l in S1. The contribution of P. micans to the total dinoflagellate density was higher and reached 99.54% in station S1. These blooms would be associated with high concentrations of chlorophyll (a) and pheopigments, which equaled 40 µg/l and 909 µg/l, respectively, and dissolved oxygen supersaturations (17.05 mg/l). This phenomenon also corresponded to a marked decrease in salinity. According to the application of the Kruskal-Wallis test, the difference was found to be significant between the three stations (p = 0.0034). In addition, densities were higher in surface water than in bottom water at all three stations. However, this difference did not appear to be statistically significant (p > 0.05).

Geopolymer concretes are considered to be a potential sustainable, low-embodied carbon alternative for Ordinary Portland Cement (OPC) concrete. Alkali leaching is considered to be a major esthetic concern for Na-silicate-based geopolymers as it can lead to the formation of efflorescence products on the surfaces of concrete members exposed to humidity. In this context, this research aims to investigate the effect of the alkali content and the FA/GGBS mass ratio on the alkali leaching and formation of the efflorescence products. Paste cylinders were fabricated and cured in ambient conditions. Samples were submerged in deionized water and the concentration of the leached-out ions was measured. Efflorescence potential was also investigated by partial immersion of the samples in deionized water. The results highlight the complexity of the interacting parameters governing the formation of efflorescence products in geopolymer materials. Establishing relationships between the concrete mix variables and the risk of efflorescence seems unfeasible particularly because of the wide range of possible precursors and activators available to design geopolymer concrete mixes. To overcome this barrier, a practical performance-based testing method is developed. For the first time, by testing a wide range of geopolymer materials, performance-based requirements associated with the risk of efflorescence for geopolymer concrete surfaces exposed to humidity are calibrated. Four categories of risk are proposed and typical suitable exposure conditions for geopolymer concrete surfaces are suggested for each risk category.

Around the world, large amounts of plastic and glass waste have been collected. This work is given as a way to reduce this material. This paper aims to investigate how fired clay bricks' physical and mechanical properties are affected by plastic/glass (P/G) powder. It is used as a replacement for clay, varying the plastic/glass content 00/20, 05/15, 10/10, 15/05, and 20/00 weight %. The ratio of soil to water remains constant 0.3. The maximum temperature is presented after three fire phases. The temperatures are 300 °C for the first, 600 °C for the second, and 900 °C for the third. Results for the physical properties showed an increase in the water absorption of clay brick specimens as the plastic content increased; in addition, efflorescence was increased with plastic powder. However, the density and firing shrinkage decrease with plastic quantity. Also, the experimental results showed a decrease in water absorption and efflorescence when the glass powder was increased. While the density is higher when glass powder is 20 %. According to the findings on mechanical properties, clay brick samples with higher plastic powder content 20 % displayed a decrease in compressive strength and flexural bending strength, i. e. the mechanical properties (compressive and flexural strengths) are increased with the increased

In this work, we investigated the drying process of a hardened gypsum plaster model (GP) that showed sodium sulfate efflorescence after subsequent exposure to water. Visible efflorescence could be prevented by adding small amounts of calcium formate (CF). Prism samples were prepared to investigate this observation, with an emphasis on chemical processes in the pore water. In the pure plaster, both sodium and sulfur accumulate at the surface of the prism, which leads to sodium sulfate precipitation. In the sample containing CF, calcium slightly accumulates at the surface, which leads to lower sulfur concentrations, because the porewater is in equilibrium with gypsum. Thermodynamic calculations show that higher sodium concentrations are then necessary to reach sodium sulfate supersaturation than without CF. These concentrations are not exceeded during early stages of the drying process, which ultimately leads to the sodium sulfate precipitation inside the prism. Therefore, sodium sulfate efflorescence can be hindered on gypsum plaster by the addition of CF. [ABSTRACT FROM AUTHOR]

This study investigates the possibility of reducing the efflorescence (excess or non-reactive salts) effect of inorganic polymers based on aluminosilicate materials from Jordan. This was achieved by minimizing the particle size of the raw materials, and using hydrothermal curing at 80° C, 120° C and 150° C, then comparing the results with other different curing conditions; ambient and humid. Kaolinite (K), volcanic tuff (Vt), and silica sand (Ss) raw materials were used. The raw materials were ground to the average particle sizes (d50) of: <10µm, <200nm, and <100nm. Three different mixing ratios of Vt, K, and Ss were used to study their dissolution behavior and to prepare inorganic polymers. X-ray diffraction (XRD), X-ray fluorescence (XRF), and inductively coupled plasma (ICP) techniques were used to identify the mineralogical and chemical composition of the raw and processed materials. The samples of <10µm were successful to be molded and analyzed for compressive strength. The average compressive strength was about 65 Mpa under hydrothermal condition cured at 150°C. The samples of nanometric size failed because the material in this range of size behaves and exhibits one or more nanoscale phenomena. Qualitative and quantitative measurements of efflorescence formation were also determined. The average alkali leaching was reduced from 3.14% of ambient cured samples to 0.83% of hydrothermally cured ones. This highest strength result indicates that the alkaline solution has reacted with the majority of Al3+ and Si4+ of silicates raw material. [ABSTRACT FROM AUTHOR]

Nous présentons ici le cas d'un patient de 38 ans ayant bénéficié d'une phalloplastie faite par lambeau perforant thoracodorsal avec conformation par enroulement en double tube. Alors que la chirurgie de reconstruction de verge a vu une efflorescence de différentes techniques opératoires, la chirurgie de réassignation femme-homme qui en découle voit ces procédés se résumer a deux ou trois options. Si le temps préopératoire fait classiquement l'objet d'une discussion avec le patient d'un allongement des voies urinaires ou non ou encore d'une implantation secondaire ou non, le choix du site donneur reste trop systématisé. Le prélèvement d'un lambeau n'est pas sans risque. L'attention est trop souvent portée sur le site reconstruit au détriment du site prélevé. Dans le cas présent, la laxité de la région dorsale avec possibilité de fermeture directe nous a fait retenir le prélèvement d'un lambeau perforant thoraco dorsal. La fonction musculaire du site donneur est préservée et l'aspect esthétique affiné par fermeture directe. La finesse du lambeau obtenu a permis la conformation par enroulement en double tube tel que décrit par Chang. La revue de la littérature rapporte un cas de phalloplastie par lambeau perforant thoracodorsal avec allongement des voies urinaires par greffe. Aucun cas n'est décrit avec conformation en double tube à notre connaissance. This article deals with a clinical case of a tube in a tube TDAP phalloplasty in a 38 years old trans-man. While penis reconstruction surgery aroused an efflorescence of different operative techniques, the resulting female to male surgery sees these procedures boil down to two or three flaps. If we usually discuss before surgery about the way to lengthen the urinary tract, as the way to implant later for intercourse; the choice of the donor site remains too systematized. Surgeons commonly focus on the reconstructed site prior to the donor site. In this case, laxity in the back and reliability of direct closure make us harvest the thoracodorsal perforator flap. Dissection of perforators saves muscular function and direct closure afford an aesthetic result less visible than a graft on the forearm. The thin flap we harvest allows tube in tube phalloplasty so that phallus and urethra are being built in the same time. One case has been reported in the literature of thoracodorsal perforator flap phalloplasty with grafted urethra, but no case of tube within a tube TDAP phalloplasty. [ABSTRACT FROM AUTHOR]

Abstract A thin, grey surface layer was noticed after removing the varnish of an eighteenth century Dutch oil painting, by an unknown artist titled Vision of Saint Lutgard of Tongeren. This layer masked the paint layer almost entirely, casting a greyish veil that greatly influenced the painting’s appearance, colour, and saturation. Using scanning electron microscopy coupled with elemental analysis (SEM–EDX), this layer was identified as a lead-rich salt crust. The crust was a distinct layer on top of the paint layer, closely following the topography of the layer underneath but not embedded in it. The article discusses the possible theories behind the formation of this lead-rich salt crust by characterizing the painting’s material, past treatments, and environmental history. Furthermore, the article reports the decision-making process behind the removal of the crust, focusing specifically on the ethical and technical challenges of the cleaning treatment. Tests with different cleaning agents targeting separate components of the crust to remove it and different application techniques are described. The chelating agent Ethylenediaminetetraacetic acid (EDTA) was found to be the most effective in the removal of the crust and was chosen for its removal. The pH of the EDTA cleaning solution and its application had to be modified according to the colour of the paint the crust lay upon. Visual observations and analytical assessments using optical microscopy and SEM after cleaning indicate a successful reduction of the crust resulting in a significant improvement in the painting’s appearance.

• Beeswax-based museum objects show efflorescence. • Efflorescence contains palmitic and stearic acids. • Efflorescence arises from a solid-solid miscibility issue. • The loss of plasticizers is detrimental to mechanical properties. The Natural History Museum of Florence, and in particular "La Specola", houses several ceroplastics collections produced in Florence in the XVIII-XIX centuries by Clemente Susini and co-workers. The collections include models of fruits and plants, vertebrate and invertebrate animals, and over 1400 anatomical waxes. All models are mainly constituted by beeswax. Although extremely resistant, the models undergo a wide range of degradation processes. Periodically, a white crystalline efflorescence, commonly called "wax bloom", appears on the surface of the objects obviously impairing their aesthetical features. Many mechanisms have been hypothesized about the formation of these white exudates, but non univocal conclusions have yet been drawn. Our gas chromatography-mass spectrometry results indicate that wax bloom strongly depends on the composition of the models, being related to the presence of oils and fats originally used as plasticizers or pigments' media. Thermal and X-ray measurements indicate that a poor solid-solid miscibility between the efflorescence compounds and other beeswax components leads to phase separation followed by migration of the immiscible materials towards the model surface. Besides, X-ray diffraction reveals an increased structural order of models as compared to recent beeswax certainly correlated with the increased brittleness determined by rheology measurements. [ABSTRACT FROM AUTHOR]

Compared with portland-cement-based matrices, the high mechanical strength, satisfactory durability, and sustainable features of geopolymeric matrices have brought great interest in the civil construction sector. Excessive activator content in a geopolymer mixture can cause efflorescence, a phenomenon related to the unreacted alkalis that compromise the mechanical properties and aesthetics of the structures. This article proposes applying statistical mixture design (SMD), associated with simultaneous optimization for the dosage of geopolymeric matrices, to evaluate and mitigate efflorescence. Based on the extreme vertices screening design, the formulations were made using metakaolin as a precursor, NaOH and sodium silicate as the activator, and sand and superplasticizer. The formulation with the lowest efflorescence formation, highest compressive strength, and adequate workability was the one whose molarity of NaOH was equal to 9.02 M, and the ratios Na2O/Al2O3 , SiO2/Al2O3 , and H2O/Na2O were equivalent to 1.43, 2.65, and 8.36, respectively. In addition, the Na2O/Al2O3 ratio was the predominant factor for efflorescence occurrence. SMD associated with simultaneous optimization is a technically viable alternative for minimizing free sodium in geopolymeric matrices. [ABSTRACT FROM AUTHOR]