Materiales activados alcalinamente porosos con liberación lenta de álcalis. Efecto de la composición

Alkali activated materials (AAM) based on calcined metakaolin or illite clay together with waste by-products, such as waste glass or aluminium scrap recycling waste, were tested as value-added materials for pH stabilization in biogas technology where decrease of pH should be avoided. Porous materials with ability to slowly leach alkalis in the water media thus providing continuous control of the pH level were obtained. XRD, FTIR, SEM and titration methods were used to characterize AAM and their leaching properties. It is clear that composition of the material has an important effect on the diffusion of alkali from structure. Namely, higher Si/Al and Na/Al molar ratios may increase pore solution transfer to the leachate. The leaching rate of alkalis from the structure of AAM is high for the first few days, decreasing over time. It was possible to calculate the buffer capacity from the mixture design of AAM.En este estudio se han ensayado materiales activados alcalinamente (AAM) basados en metacaolín o arcilla de ilita junto con subproductos tales como residuos de vidrio o aluminio reciclado, como materiales con valor añadido para la estabilización del pH en tecnologías de biogás donde se debe evitar la disminución del pH . Se obtuvieron materiales porosos con capacidad para lixiviar lentamente los álcalis en medios acuosos, proporcionando así un control continuo del nivel de pH. Se utilizaron técnicas de DRX, FTIR, SEM y métodos de tritación para caracterizar los AAMs y sus propiedades de lixiviación. La composición del material tiene un efecto importante en la difusión del álcali de la estructura. Es decir, mayores relaciones molares de Si / Al y Na / Al pueden aumentar la transferencia de la solución del poro al lixiviado. La tasa de lixiviación de los álcalis desde la estructura de los AAMs es alta durante los primeros días, disminuyendo con el tiempo. Se ha calculado la capacidad del efecto tampón a partir del diseño de mezcla de AAM

The Thermal Characteristics Of Gypsum Boards With Phase Change Materials (PCM)

Two types of PCM were investigated for use in phase change gypsum boards: salt hydrate and paraffin. The transition temperatures, or melting temperatures, of the PCM is near to standard or suggested room temperatures 20-21 °C for heating-dominated climates or 25-27 °C for cooling-dominated climates. Phase change gypsum boards were produced by using three different methods: simple immersion for 1 hour and direct incorporation of raw and microencapsulated PCMs in 5 and 10% of composition mass. PCM were tested and the effects of energy conservation of PCM gypsum boards were determined. Also some physical and mechanical properties were determined to investigate the effect of PCM addition to gypsum boards

Addressing the need for standardization of test methods for self-healing concrete: an inter-laboratory study on concrete with macrocapsules.

Development and commercialization of self-healing concrete is hampered due to a lack of standardized test methods. Six inter-laboratory testing programs are being executed by the EU COST action SARCOS, each focusing on test methods for a specific self-healing technique. This paper reports on the comparison of tests for mortar and concrete specimens with polyurethane encapsulated in glass macrocapsules. First, the pre-cracking method was analysed: mortar specimens were cracked in a three-point bending test followed by an active crack width control technique to restrain the crack width up to a predefined value, while the concrete specimens were cracked in a three-point bending setup with a displacement-controlled loading system. Microscopic measurements showed that with the application of the active control technique almost all crack widths were within a narrow predefined range. Conversely, for the concrete specimens the variation on the crack width was higher. After pre-cracking, the self-healing effect was characterized via durability tests: the mortar specimens were tested in a water permeability test and the spread of the healing agent on the crack surfaces was determined, while the concrete specimens were subjected to two capillary water absorption tests, executed with a different type of waterproofing applied on the zone around the crack. The quality of the waterproofing was found to be important, as different results were obtained in each absorption test. For the permeability test, 4 out of 6 labs obtained a comparable flow rate for the reference specimens, yet all 6 labs obtained comparable sealing efficiencies, highlighting the potential for further standardization

Evaluation of Methodologies for Assessing Self-Healing Performance of Concrete with Mineral Expansive Agents: An Interlaboratory Study

Self-healing concrete has the potential to optimise traditional design approaches; however, commercial uptake requires the ability to harmonize against standardized frameworks. Within EU SARCOS COST Action, different interlaboratory tests were executed on different self-healing techniques. This paper reports on the evaluation of the effectiveness of proposed experimental methodologies suited for self-healing concrete with expansive mineral additions. Concrete prisms and discs with MgO-based healing agents were produced and precracked. Water absorption and water flow tests were executed over a healing period spanning 6 months to assess the sealing efficiency, and the crack width reduction with time was monitored. High variability was reported for both reference (REF) and healing-addition (ADD) series affecting the reproducibility of cracking. However, within each lab, the crack width creation was repeatable. ADD reported larger crack widths. The latter influenced the observed healing making direct comparisons across labs prone to errors. Water absorption tests highlighted were susceptible to application errors. Concurrently, the potential of water flow tests as a facile method for assessment of healing performance was shown across all labs. Overall, the importance of repeatability and reproducibility of testing methods is highlighted in providing a sound basis for incorporation of self-healing concepts in practical applications

Novel porous fly ash-containing geopolymers for pH buffering applications

In this work novel, porous biomass fly ash-containing geopolymers with high pH buffer capacity and tailored alkalis leaching were produced by using hydrogen peroxide as blowing agent. Results demonstrate that the geopolymers leaching rate can be controlled by the hydrogen peroxide content and by the solids-to-liquid ratio during geopolymers preparation. Total leaching of hydroxyl ions from the porous geopolymers ranged between 0.0104 and 0.0180 mol/(dm(3) g). Higher solids-to-liquid ratios promoted a gentler alkalis leaching from the geopolymers, while higher porosities shifted the initial pH towards higher values without compromising their buffering ability. The excellent ability to control pH over time shown by these novel geopolymers demonstrates their potential as pH regulators in applications where high buffer capacity is required. Furthermore the reuse of biomass fly ash in these innovative materials reduces the environmental footprint associated with this waste disposal. (C) 2016 Elsevier Ltd. All rights reserved

Design and synthesis of non-TZD peroxisome proliferator-activated receptor γ (PPARγ) modulator

Thiazolidinediones (TZDs) are an important class of compound used for the treatment of type 2 diabetes, targeting the peroxisome proliferator-activated receptor γ (PPARγ). Drug-induced hepatotoxicity, edema, and weight gain are the main concerns associated with TZDs. It was unclear whether the side effects observed are target mediated or compound mediated, but most of the TZDs activate PPARγ. This obliged developing of a new diverse class of ligands as antihyperglycemic agents including non-TZD PPAR ligands that could be highly effective, safe, and devoid of side effects. Here, we report the design and synthesis of N-(5-chloro-6-((1-phenylpiperidin-4-yl)oxy)pyridin-3-yl) benzenesulfonamide derivatives as non-TZD PPARγ modulators. © Springer Science+Business Media 2013