Epsomite as flame retardant treatment for wood: Preliminary study

The effect of epsomite as flame retardant for wood has been investigated and compared with a commercial boron salt. Both flame retardants have been introduced into wood samples by vacuum impregnation. Epsomite is a hydrated sulphate salt with a water solubility of 731 g L-1 at room temperature. Thanks to this high solubility it was possible to obtain elevated epsomite loadings in comparison with the borax salt. Flame retardancy was evaluated by means of the limiting oxygen index, the dripping test and the exposition to a direct flame (Bunsen test). The results showed that the addition of epsomite increases the limiting oxygen index, delays the time to ignition and the evolution of the temperatures trough the wood. © 2016 Elsevier LtdPeer ReviewedPostprint (author's final draft

High-porosity alkali-activated binders based on glass and aluminium recycling industry waste

The potential as alkali-activated precursors of ceramic-stone-porcelain (CSP) and PAVAL, two residues derived from the optical separation of glass cullet and salt slag from secondary aluminium recycling, has been assessed. Alkali-activated CSP and PAVAL binders’ formulations were prepared using NaOH 4 M and 6 M as alkaline activator solutions. The effect of the Na2O/Al2O3 ratio and alkaline activator concentration was evaluated from a chemical, physical, mechanical, and environmental perspective. The results revealed the formation of secondary reaction products attributed to the formation of (C,N)-A-S-H gels. It also showed the influence of decreasing Na2O/Al2O3 ratio in the obtained binders, increasing porosity and affecting the mechanical performance. Besides, it was demonstrated that PAVAL acts as a precursor and pore-generator. Finally, the environmental characterisation showed a significant leaching concentration of heavy metal(loid)s such as As, Cr, Mo, Sb, and Se, which decreases with longer curing periods.This work is partially supported by the Grants PID2021-125810OB-C21 and TED2021-129718B-I00, funded by MCIN/AEI/https://doi.org/10.13039/501100011033 , by “ERDF A way of making Europe”, and by the “European Union NextGenerationEU/PRTR”, and the Agència de Gestió d’Ajuts Universitaris i de Recerca (AGAUR) with the Grant 2021 SGR 00708. The authors would like to thank Daniel Rosas, S.A. for supplying the CSP, and Befesa Company for supplying the PAVAL. Mr Jofre Mañosa is grateful to the Government of Catalonia for its research Grant (FI-DGR 2020). Dr Teresa López-Montero is supported by the Spanish grant Juan de la Cierva Formación referenced as FJC-2018-035747-I.Peer ReviewedPostprint (published version

Analysing the potential use of a low-grade magnesium carbonate by-product as a filler in hot asphalt mixtures

This is an Accepted Manuscript of an article published by Taylor & Francis Group in International Journal of Pavement Engineering on 2022, available online at: http://www.tandfonline.com10.1080/10298436.2022.2083618.Climate change and natural resources depletion are leading society towards a more environmentally sustainable approach. In areas such as construction or civil engineering, waste and by-products valorisation could help in the fight against climate change, reducing the consumption of raw materials. Thus, the use of residues or by-products in asphalt mixtures manufacturing as road pavement layers has great potential due to their characteristics and the large number of natural resources required. Thus, this research aims to characterise a flotation sterile (Low-Grade Magnesium Carbonate, LG-MC) generated in the beneficiation process of natural magnesite and analyse its potential use as filler in asphalt mixtures manufacturing. The characterisation of physical, chemical, and microscopic properties of LG-MC was carried out and then its potential use as filler for asphalt mixtures was evaluated using the UCL (Universal de Caracterización de Ligantes) method. The optimum filler/bitumen ratio for the LG-MC was 1.49, higher than that of calcium carbonate, which was 1.33. Results show a protective effect of LG-MC as filler against ageing, both in the short and long-term, reducing losses due to abrasion.This work was supported under Grant FJC-2018-035747-I funded by MCIN/AEI/10.13039/501100011033; by the Magnesitas Navarras S.A. under Grant FGB 311127; and Government of Catalonia under Grant FI-DGR 2020.Peer ReviewedObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraPostprint (author's final draft

Magnesium phosphate cement formulated with low grade magnesium oxide with controlled porosity and low thermal conductivity as a function of admixture

Magnesium phosphate cement (MPC) formulated with low-grade magnesium oxide (LG-MgO) can be better considered as sustainable MPC (sust-MPC). Among other properties, sust-MPC could be used as building material for constructive elements because of its acoustic and thermal insulation properties. Porosity and thermal conductivity are two important parameters that have a significant influence on thermal insulation properties. In this regard, this work aimed to obtain a highly porous sust-MPC with enhanced properties for thermal insulation. To this end the percentage of porosity as a function of both the amount of set-retarding admixture and the kneading water needed was assessed using a statistical design of experiments (DoE) approach. Additionally, thermal conductivity was also evaluated with respect these two factors. Last but not least, an optimized dosage was sought in order to maximize the percentage of porosity while achieving the lowest thermal conductivity. According to the results obtained, the statistical method successfully predicted the effects of variables on the final properties. Hence, a model that explains the overall behaviour of the system was successfully attained. The obtained model predicts the porosity and the thermal conductivity of sust-MPC by means of the mixture dosage. Consequently, the present work demonstrates that it is possible to control the porosity in order to diminish thermal conductivity. Keywords Insulation; building material; design of experiments; MPC; porosity; thermal conductivit

Chemically bonded cements formulated with by-products of magnesium oxide

The casting of magnesium and potassium phosphate (KMgPO4•6H2O; K-struvite) cements becomes possible after the aqueous reaction between magnesium oxide and potassium dihydrogen phosphate. This reaction is quite exothermic and allows the resulting paste setting in just few minutes. Those cements, when are cast with magnesium oxides of high purity, are used to retain and encapsulate special residues and as repairing concrete mortar, as it is described in the bibliography. However, it is also possible formulate those cements using low grade magnesium oxides, which cost are nearly 10 or 15 times cheaper than those of high grade. The aim of this work is to evaluate the possibility of using low grade magnesium oxides (˜70% MgO), obtained from the calcinations process of natural magnesites, for KMgPO4•6H2O cement casting. The research and selection of the best formulation for obtaining that cement will be done also from the point of view of their mechanical properties as for their setting time.Peer ReviewedPostprint (published version

Magnesium phosphate cements formulated with low grade magnesium oxide incorporating phase change materials for thermal energy storage

Magnesium Phosphate Cement (MPC) has become an essential reference for investigators seeking alternatives to the use of Ordinary Portland Cement (OPC) in building sector because of its high environmental impact. The research group developed a MPC formulated with low-grade MgO (LG-MgO) by-product, which could be considered as a sustainable MPC (sust-MPC). This research focuses on the incorporation of different percentages of Microencapsulated Phase Change Materials (MPCM) into sust-MPC, due to their ability to reduce energy consumption of heating, ventilating, and air conditioning (HVAC) systems. The study consists of an exhaustive characterization of thermal sustainable MPC (TS-MPC) dosages which incorporate air-entraining additive (AEA) and MPCM to improve their thermal behaviour. Thus, TS-MPC would reduce the use of HVAC systems contributing to the decrease of CO2 emissions and increasing energy efficiency in buildings. Moreover, properties such as bulk density, porosity, thermal conductivity, modulus of elasticity, compressive strength, and flexural strength are analysed to evaluate the potential use of these cements as a part of a passive conditioning system. Results show the proper behaviour of these cements to reduce thermal oscillation in buildings. Experimental results demonstrated the relation between the amount of the MPCM and the AEA percentage as well as the thermal and mechanical properties of the TS-MPC due to their contribution to increase the porosity. Furthermore, it should be noted the increase of porosity and the reduction of thermal conductivity of the optimal formulation, which are 60% higher and 50% lower than the sust-MPC obtained without MPCM and additive, respectively.Postprint (author's final draft

Crushed autoclaved aerated concrete (CAAC), A potential reactive filter medium for enhancing phosphorus removal in nature-based solutions-preliminary batch studies

Phosphorus (P) is a limited resource and can promote eutrophication of water streams and acidification of oceans when discharged. Crushed autoclaved aerated concrete (CAAC), a by-product from demolition, has shown great potential for recovering P. The potential of CAAC to be used in nature-based solutions as a P-reactive filter medium was evaluated by performing preliminary batch essays. Here, we evaluated the interactions and main effects of the initial concentration of P (Pi; 5, 10 or 20 mg L-1), particle size (PS; 4 or 5 mm) and contact time (CT; 60, 180, 360, 720 and 1440 min) upon the removal. We performed physical and chemical characterization to understand the removal processes. Data collected were fitted in adsorption kinetic models. The statistical analysis showed a significant interaction between CT and Pi, with the combination of its main effects stronger on P removal than each one separately. Intriguingly, we noticed that the higher the concentration of Pi, the faster and higher the removal of P. Contrary to expectations, PS 5 mm showed higher removal rates than PS 4 mm, indicating that besides adsorption, other unidentified chemical processes are in place. Further studies using columns/pilots with real wastewater are recommended for a future follow-up.Peer ReviewedPostprint (published version

Cementos químicos formulados con subproductos de óxido de magnesio

Es posible obtener cementos de fosfato de magnesio y potasio (KMgPO4·6H2O; K-estruvita), mediante la reacción en medio acuoso del óxido de magnesio y el dihidrogenofosfato de potasio, siendo ésta una reacción exotérmica muy rápida que permite el fraguado del material en pocos minutos. Estos cementos, formulados a partir de óxidos de magnesio de elevada pureza y coste elevado, se encuentran descritos en la bibliografía para su utilización en el encapsulamiento de residuos especiales y como morteros de cemento para la reparación de hormigón. Sin embargo cabe la posibilidad de poder formular este mismo tipo de cementos con óxidos de magnesio de bajo contenido, cuyo precio es del orden de 10 a 15 veces más barato que el óxido de magnesio de elevada pureza. En el presente estudio se evalúa la utilización de óxidos de magnesio de bajo contenido (≈70% MgO), obtenidos en el proceso de calcinación de la magnesita natural, para la formulación de cementos de K-estruvita. En este estudio se pretende determinar la formulación óptima de estos cementos a partir de la evaluación tanto de las propiedades mecánicas como de los tiempos de fraguado de las diferentes composicionesPeer ReviewedPostprint (published version

Maritime distress watch by HM Coastguard

SIGLEAvailable from British Library Document Supply Centre-DSC:5375.57145(63) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Uniform convergence to the spectral radius and some related properties in Banach algebras

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN016804 / BLDSC - British Library Document Supply CentreGBUnited Kingdo