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Ettringite binder is widely used in mortars for technical applications such as patching mortars, self-leveling screeds, repair mortars thanks to their fast hardening ability and high early strength. However, depending on the amount and types of raw materials used in the composition, the properties of these types of binder have different behaviors at early-age and at long term. In this work, the influence of the nature and dosage of calcium sulfate in ettringite binder on the long-term strength of mortar in different curing conditions was determined. The results showed that the increase of calcium sulfate content in ettringite binder from 10–25 % improves the strength of mortars regardless of the calcium sulfate nature. In all curing conditions (endogenous, drying, outdoor), the strength of ettringite mortars with anhydrite is smaller than that of mortars containing hemihydrate. There is no major difference in the porosity of the mortars in different types of curing conditions before 28 days. However, after 28 days the porosity of mortar in drying condition is about 2–3 % higher than that of the mortars in endogenous and outdoor conditions.

Local scale imaging techniques (SEM, CT) and global characterisation tools (X-ray diffraction, TG-DTA, and Fourier Transform Infrared microscope (FTIR)) have been used for years so as to formulate building materials and overcome or understand degradation processes. The objective of this study is to obtain local quantitative information on covalent bonds using a FTIR. Some experimental and theoretical aspects of the chemical mapping are detailed, and illustrated by a study on a model material (hydrated cement, limestone filler and styrene-butyl-acrylate latex). Main experimental setups, post-processing and spectra deconvolution methods are thoroughly discussed. Difficulties arisen from the acquisition technique are illustrated on organic-inorganic material. To enable a reliable quantitative analysis of data, a homemade algorithm is suggested, founded on both statistical considerations (SIMPLISMA algorithm), and iterative penalised resolution (Alternative Least Square). This algorithm implemented on MATLAB leads to a fair spatial distribution of relative concentration for each component of the model cement/latex material. [ABSTRACT FROM AUTHOR]

The geomaterial foams studied is based on geopolymerization reactions, which is a type of geosynthesis that involves silico-aluminates. Its study during formation has however revealed a different behavior than geopolymer, suggesting the formation of various networks. This work investigates the interaction between initial compounds (metakaolin, silica fume, potassium-based solution) by a kind of mixture decomposition to ultimately understand the formation mechanism of foam. The structural evolution was determined using thermal analysis, FTIR spectroscopy and Al and Si MAS-NMR measurements. The use of different raw materials in combination with various solutions demonstrates the formation of various species in solution. The reactivity of the solution will then evolve in different ways. The Si/K ratio controlled the type of species created and, particularly, the reactivity in the mixture. From the various reactions of dissolution and polycondensation that were deduced, we could identify the composition of the four networks (KSiAlOH; KSiO; KAlSiO,1.5HO; and amorphous silica) constituting the foam. [ABSTRACT FROM AUTHOR]

The management of Waste-to-Energy Bottom Ash (WtE-BA), generated during the incineration of waste, poses a global challenge. Presently, the majority of WtE-BA is disposed of in landfills due to the lack of alternatives. Meanwhile, the construction industry remains the primary consumer of raw materials and significantly contributes to Greenhouse Gas Emissions. This study attempts to address these issues by utilizing the fine fraction of WtE-BA (<2 mm) as a raw material for aerated mortar production. Thanks to its metallic aluminum content, WtE-BA is utilized as an aerating agent. The study investigates how the quantities of water and WtE-BA, as well as its granulometric sub-fractions, impact the properties of the final product. An analysis of properties such as density, compressive strength, and thermal conductivity was conducted. Additionally, the environmental impact of each raw material (i.e. WtE-BA, cement and sand) was assessed through leaching tests and elemental content analysis enabling the determination of their individual contribution to the presence of trace elements in the produced mortars. The aforementioned properties are discussed using microstructure and porosity analyses. The findings demonstrate that the quantity of water is a crucial factor in controlling the aeration of mortars, whereas the granulometry of the WtE-BA particles did not significantly affect their macro-properties. Furthermore, this study highlights that WtE-BA based mortars has the potential to exhibit better environmental and insulating performances than standard aerated mortar of equal density and strength. The differences in pore size and type between WtE-BA and aerated mortars can account for the variation in performance. Thus, WtE-BA proves to be an effective substitute for aerating agent in the production of aerated mortars., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

The objective of this study is to determine the influence of recycled glass powder (GP) on the physico-mechanical behavior and durability of a ternary cementitious binder containing calcined clay&#95;metakaolin (MK) or rice husk ash (RHA). Different mortars were produced and characterized in fresh and hardened states. Reference mortars were produced using 100% cement CEM II/B-L 42.5R and 70% CEM + 30% MK or RHA. Test mortars were produced with the substitution of the MK or RHA with the GP and keeping the rate of the substitution at 30%; i.e., in ratios of 20:10, 15:15, and 20:10 of MK/RHA:GP. The water/binder weight ratio was maintained at 0.5, and the consistency of all mortars was adjusted using an admixture (superplasticizer/binder weight ratio of 0.75%). The substitution of MK and RHA with GP reduces the water demand to achieve the normal consistency of pastes and therefore increases the workability of mortars containing both binders CEM+MK+GP and CEM+RHA+GP. The substitution of MK and RHA with GP slightly reduces the compressive strength for both binders. The water-accessible porosity slightly increases for the substitution of MK and reduces for the substitution of RHA with GP. The mass losses after acid attack slightly increase with the substitution with GP, lower for the MK than the RHA up to 15% GP, but it remained far below that of 100% CEM. The results show that the substitution of MK and RHA with GP can improve the physical properties and durability of the mortars compared with that of 100% CEM, but it slightly decreases the mechanical properties due to the low rate of the pozzolanic reactivity of the GP. Further studies should seek to understand the reactivity behavior of the GP at the microstructure scale and therefore improve the mechanical performance of GP based mortar.

Background: The goal of this study was to determine whether an awake prone position (aPP) reduces the global inhomogeneity (GI) index of ventilation measured by electrical impedance tomography (EIT) in COVID-19 patients with acute respiratory failure (ARF)., Methods: This prospective crossover study included COVID-19 patients with COVID-19 and ARF defined by arterial oxygen tension:inspiratory oxygen fraction ( P aO 2 : F IO 2 ) of 100-300 mmHg. After baseline evaluation and 30-min EIT recording in the supine position (SP), patients were randomised into one of two sequences: SP-aPP or aPP-SP. At the end of each 2-h step, oxygenation, respiratory rate, Borg scale and 30-min EIT were recorded., Results: 10 patients were randomised in each group. The GI index did not change in the SP-aPP group (baseline 74±20%, end of SP 78±23% and end of aPP 72±20%, p=0.85) or in the aPP-SP group (baseline 59±14%, end of aPP 59±15% and end of SP 54±13%, p=0.67). In the whole cohort, P aO 2 : F IO 2 increased from 133±44 mmHg at baseline to 183±66 mmHg in aPP (p=0.003) and decreased to 129±49 mmHg in SP (p=0.03)., Conclusion: In spontaneously breathing nonintubated COVID-19 patients with ARF, aPP was not associated with a decrease of lung ventilation inhomogeneity assessed by EIT, despite an improvement in oxygenation., Competing Interests: Conflict of interest: L. Papazian received consultancy fees from Air Liquide MS, Faron and MSD outside the submitted work. C. Guervilly received fees from Xenios FMC outside the submitted work. The other authors declare no competing interests., (Copyright ©The authors 2023.)

To determine the effect of the awake prone position (APP) on gas exchange and the work of breathing in spontaneously breathing patients with COVID-19-associated acute hypoxemic respiratory failure (AHRF) supported by high-flow nasal oxygen., Design: Prospective randomized physiologic crossover multicenter trial., Settings: Four ICUs in Marseille, France., Patients: Seventeen patients with laboratory-confirmed COVID-19 pneumonia and Pao 2 /Fio 2 less than or equal to 300 mm Hg while treated with high-flow nasal cannula oxygen therapy., Interventions: Periods of APP and semirecumbent position (SRP) were randomly applied for 2 hours and separated by a 2-hour washout period., Measurements and Main Results: Arterial blood gases, end-tidal CO 2 . and esophageal pressure were recorded prior to and at the end of each period. Inspiratory muscle effort was assessed by measuring the esophageal pressure swing (∆P ES ) and the simplified esophageal pressure-time product (sPTP ES ). The other endpoints included physiologic dead space to tidal volume ratio (V D /V T ) and the transpulmonary pressure swing. The APP increased the Pao 2 /Fio 2 from 84 Torr (61-137 Torr) to 208 Torr (114-226 Torr) ( p = 0.0007) and decreased both the V D /V T and the respiratory rate from 0.54 (0.47-0.57) to 0.49 (0.45-0.53) ( p = 0.012) and from 26 breaths/min (21-30 breaths/min) to 21 breaths/min (19-22 breaths/min), respectively ( p = 0.002). These variables remained unchanged during the SRP. The ∆P ES and sPTP ES per breath were unaffected by the position. However, the APP reduced the sPTP ES per minute from 225 cm H 2 O.s.m -1 (176-332 cm H 2 O.s.m -1 ) to 174 cm H 2 O.s.m -1 (161-254 cm H 2 O.s.m -1 ) ( p = 0.049)., Conclusions: In spontaneously breathing patients with COVID-19-associated AHRF supported by high-flow nasal oxygen, the APP improves oxygenation and reduces the physiologic dead space, respiratory rate, and work of breathing per minute., Competing Interests: The authors have disclosed that they do not have any potential conflicts of interest., (Copyright © 2022 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the Society of Critical Care Medicine.)

Prone positioning reduces mortality in the management of intubated patients with moderate-to-severe acute respiratory distress syndrome. It allows improvement in oxygenation by improving ventilation/perfusion ratio mismatching.Because of its positive physiological effects, prone positioning has also been tested in non-intubated, spontaneously breathing patients, or "awake" prone positioning. This review provides an update on awake prone positioning for hypoxaemic respiratory failure, in both coronavirus disease 2019 (COVID-19) and non-COVID-19 patients. In non-COVID-19 acute respiratory failure, studies are limited to a few small nonrandomised studies and involved patients with different diseases. However, results have been appealing with regard to oxygenation improvement, especially when combined with noninvasive ventilation or high-flow nasal cannula.The recent COVID-19 pandemic has led to a major increase in hospitalisations for acute respiratory failure. Awake prone positioning has been used with the aim to prevent intensive care unit admission and mechanical ventilation. Prone positioning in conscious, non-intubated COVID-19 patients is used in emergency departments, medical wards and intensive care units.Several trials reported an improvement in oxygenation and respiratory rate during prone positioning, but impacts on clinical outcomes, particularly on intubation rates and survival, remain unclear. Tolerance of prolonged prone positioning is an issue. Larger controlled, randomised studies are underway to provide results concerning clinical benefit and define optimised prone positioning regimens., Competing Interests: Conflict of interest: F. Touchon has nothing to disclose. Conflict of interest: Y. Trigui has nothing to disclose. Conflict of interest: E. Prud'homme has nothing to disclose. Conflict of interest: L. Lefebvre has nothing to disclose. Conflict of interest: A. Giraud has nothing to disclose. Conflict of interest: A-M. Dols has nothing to disclose. Conflict of interest: S. Martinez has nothing to disclose. Conflict of interest: M. Bernardi has nothing to disclose. Conflict of interest: C. Begne has nothing to disclose. Conflict of interest: P. Granier has nothing to disclose. Conflict of interest: P. Chanez reports grants and personal fees from Almirall, Boehringer Ingelheim, ALK, GSK, AstraZeneca, Novartis, Teva and Chiesi, and grants from AMU, outside the submitted work. Conflict of interest: J-M. Forel has nothing to disclose. Conflict of interest: L. Papazian has nothing to disclose. Conflict of interest: X. Elharrar has nothing to disclose., (Copyright ©The authors 2021.)

It is unknown if solid organ transplant recipients are at higher risk for severe COVID-19. The management of a lung transplantation (LTx) program and the therapeutic strategies to adapt the immunosuppressive regimen and antiviral measures is a major issue in the COVID-19 era, but little is known about worldwide practice. We sent out to 180 LTx centers worldwide in June 2020 a survey with 63 questions, both regarding the management of a LTx program in the COVID-19 era and the therapeutic strategies to treat COVID-19 LTx recipients. We received a total of 78 responses from 15 countries. Among participants, 81% declared a reduction of the activity and 47% restricted LTx for urgent cases only. Sixteen centers observed deaths on waiting listed patients and eight centers performed LTx for COVID-19 disease. In 62% of the centers, COVID-19 was diagnosed in LTx recipients, most of them not severe cases. The most common immunosuppressive management included a decreased dose or pausing of the cell cycle inhibitors. Remdesivir, hydroxychloroquine, and azithromycin were the most proposed antiviral strategies. Most of the centers have been affected by the COVID-19 pandemic and proposed an active therapeutic strategy to treat LTx recipients with COVID-19., (© 2020 The American Society of Transplantation and the American Society of Transplant Surgeons.)

This study explored the pozzolanic reactivity of granite powder (GP) and its influence on the microstructure of cement paste. An analysis of the physical properties (water demand, setting time, heat of hydration and total shrinkage), compressive strength and durability indicators (water absorption, porosity, acid attack and chloride ions diffusion) was carried out on mortar containing 10%, 15% and 20% of GP as partial substitution to cement (CEM I 42.5 R) in the short and long term. The results showed that the GP does not exhibit pozzolanic reactivity and that it reduces the heat of hydration. Water demand and setting time were not affected by the GP. The compressive strength decreases with increasing the content of GP; but in the long term, the compressive strength was not affected for 10% GP substitution. The presence of granite powder in mortar induces an increase in porosity, which led to an increase in the diffusion properties of fluids (capillary water absorption and chloride ions diffusion).

Background: Infection is the most common cause of mortality within the first year after lung transplantation (LTx). The management of perioperative antibiotic therapy is a major issue, but little is known about worldwide practices., Methods: We sent by email a survey dealing with 5 daily clinical vignettes concerning perioperative antibiotic therapy to 180 LTx centers around the world. The invitation and a weekly reminder were sent to lung transplant specialists for a single consensus answer per center during a 3-month period., Results: We received a total of 99 responses from 24 countries, mostly from Western Europe (n = 46) and the USA (n = 34). Systematic screening for bronchial recipient colonization before LTx was mostly performed with sputum samples (72%), regardless of the underlying lung disease. In recipients without colonization, antibiotics with activity against gram-negative bacteria resistant strains (piperacillin / tazobactam, cefepime, ceftazidime, carbapenems) were reported in 72% of the centers, and antibiotics with activity against methicillin-resistant Staphylococcus aureus (mainly vancomycin) were reported in 38% of the centers. For these recipients, the duration of antibiotics reported was 7 days (33%) or less (26%) or stopped when cultures of donor and recipients were reported negatives (12%). In recipients with previous colonization, antibiotics were adapted to the susceptibility of the most resistant strain and given for at least 14 days (67%)., Conclusion: Practices vary widely around the world, but resistant bacterial strains are mostly targeted even if no colonization occurs. The antibiotic duration reported was longer for colonized recipients.