Effect of Metallic Waste Addition on the Physical and Mechanical Properties of Cement-Based Mortars

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).This paper investigates the influence of the type and amount of recycled metallic waste on the physical and mechanical properties of cement-based mortars. The physical and mechanical properties of cement mortars, containing four different amounts of metallic waste (ranged 4 to 16% by cement weight), were evaluated by measuring the bulk density, total porosity, flexural and compressive resistance, and dynamic elastic modulus by ultrasonic tests. All the properties were measured on test specimens under two curing ages: 7 and 28 days. Additionally, the morphological properties and elemental composition of the cement and metallic waste were evaluated by using Scanning Electron Microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS), and X-ray fluorescence (XRF). Main results showed that the addition of metallic waste reduced the bulk density and increased the porosity of the cement-based mortars. Furthermore, it was observed that flexural and compressive strength proportionally increased with the metallic waste addition. Likewise, it was proven that elastic modulus, obtained by compressive and ultrasonic tests, increases with the metallic waste amount. Finally, based on a probability analysis, it was confirmed that the addition of metallic waste did not present a significant effect on the mechanical performance of the cement-based mortars.Peer reviewedFinal Published versio

Comparacion de opciones de financiamiento para maquinaria maderera

90 p.En el siguiente estudio, se efectuó una comparación económica - financiera de dos alternativas de financiamiento. Las alternativas consideradas fueron un crédito comercial bancario y un leasing financiero, para una inversión en una sierra huincha gemela. La evaluación de ambas alternativas se realizo mediante el criterio del valor actual de costos (VAC). La alternativa de leasing financiero resulto ser mas económica que la de crédito comercial bancario

Diagnóstico y propuesta de intervención en calidad de vida profesional de los trabajadores de un liceo de la ciudad de Talca

63 p.Mediante el presente estudio se determinó el nivel de Calidad de Vida Laboral (CVL) y sus dimensiones (apoyo directivo, motivación intrínseca y carga de trabajo) en los 30 profesores (14 mujeres y 16 hombres) de un Liceo de la ciudad de Talca afectado por dos desastres consecutivos y su consiguiente crisis de infraestructura. Para esta evaluación se utilizó el Cuestionario de Calidad de Vida Profesional CVP-35.Los principales resultados apuntan a un nivel medio bajo de la CVL (M=4,4) y de sus dimensiones apoyo directivo (M=5,5) y carga de trabajo (M=5,5). Por otro lado, la dimensión motivación intrínseca posee un nivel medio alto de desarrollo (M=6,5). Finalmente, con el fin de hacer más eficiente el proyecto de intervención propuesto, se correlaciona la CVL con sus dimensiones, encontrándose relaciones significativas entre 3 de las 6 posibles relaciones: apoyo directivo con motivación intrínseca (r=,635; p<,01) y con CVP (r=,463; p<,01). Dada la importancia detectada del apoyo directivo y de la motivación intrínseca en la CVL, se diseñó una intervención sustentada en el modelo bifactorial de Frederick Herzberg. Se pretende aumentar la CVL y la satisfacción de los profesores mejorando las variables motivadoras (en este caso, la motivación intrinseca y el apoyo directivo), en lugar de mejorar las variables higiénicas que producen insatisfacción (en este caso, la carga laboral). De esta manera, se plantea realizar un coaching a la plana directiva del establecimiento y una intervención potenciadora de la motivación intrínseca, como los dos procedimientos de intervención más importante

A novel type cold mix pavement material made with calcium-alginate and aggregates

This paper has been prepared in the frame of a research focused on the development of Cold Mix pavement materials made with calcium-alginate Capsules (CMC) instead of with just bitumen emulsion, as it is normally made. The initial objective was to remove most of the water in cold mix asphalt by encapsulating bitumen droplets. The encapsulation method allowed the preparation of polynuclear capsules with bitumen emulsion encapsulated, which membrane was made of calcium-alginate. Capsules were mixed with aggregates at the ambient temperature. During mixing, the capsules containing bitumen emulsion would break, release their content and coat the aggregates. To study CMC, an extensive experimental programme has been carried out to evaluate the effect of compaction energy, cement content, curing time and binder type on the mechanical properties of CMC. It was found that CMC test samples increased their Marshall stability linearly with the increase of the compaction energy. Test samples could be demoulded immediately after compaction. Furthermore, the Marshall stability of CMC increased with the curing time, and the general strength improved with the increasing amount of capsules in the mixture. It was found that the bitumen in CMC did not have an important role on the strength of the pavement material, which came mainly from the alginate in the capsules. In short, cold mix pavement materials made with calcium-alginate (Ca-alginate) capsules is a novel material for pavements that has shown potential to be an alternative for conventional cold mix asphalt made with bitumen emulsion

Experimental evaluation of cement mortars with recycled brass fibres from the electrical discharge machining process

This paper aims to evaluate the effect of recycled brass fibres on the physical, thermal and mechanical properties of cementitious mortars. For that purpose, seven different mortars, with the same water/cement ratio but using two different brass fibres were manufactured. Not-machined brass fibres were used as a reference and compared to the waste brass fibres obtained as a by-product of wire cutting methods through electrical discharge machines. Both fibres were added to the mortars in proportions of 0.25%, 0.5% and 1% by volume of mortar. The morphology and presence of elements in the fibres were evaluated by scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). In addition, ultrasonic pulse velocity and thermal conductivity were measured to evaluate the mortar quality and the fibre dispersion into the mortar specimens. Mechanical properties were studied through flexural and compression tests. Since the fibres present a reduced length, the effect on both porosity and bulk density is negligible and the reduction on ultrasonic pulse velocity and compression strength and the slight increment on flexural strength is not remarkable due to the limited anchorage provided. Nonetheless, the improvement in the thermal conductivity of the developed mortars with recycled brass fibres, supports focusing on the niche market of heating installations, such as underfloor heating or closed-loop geothermal heat exchangers.This work has been partly financed within the European Horizon 2020 Joint Technology Initiative Shift2Rail through contract no. 826255 (IN2TRACK2). This work has also been co-financed with the project Elkartek 2019 ref. KK-2019/00023 (GOLIAT2). The authors also wish to thank the Basque Government for financial assistance through IT919-16 and IT1314-19

Thermal and Mechanical Properties of Mortars Reinforced with Recycled Brass Fibres

This paper aims to encourage the circular economy and merge the manufacturing and the construction industries, providing waste fibres from the electrical discharge machining of the former as raw material for the latter. The research analyses the effect on the physical, thermal and mechanical properties of mortars reinforced with brass fibres. The manuscript deals with different fibre length (10 mm, 15 mm and 25 mm) in variable percentages (0.5%, 1%, 2% and 4%). Larger amounts and longer fibres tend to increase the thermal conductivity whereas post cracking flexural strength is more dependent on fibre length.This work has been partly financed within the European Horizon 2020 Joint Technology Initiative Shift2Rail through contract no. 826255 (IN2TRACK2) . This work has also been cofinanced with the project Elkartek 2019 ref. KK-2019/00023 (GOLIAT2) . The authors also wish to thank the Basque Government for financial assistance through IT919-16 and IT131419

Experimental evaluation of cement mortars with recycled brass fibres from the electrical discharge machining process

This paper aims to evaluate the effect of recycled brass fibres on the physical, thermal and mechanical properties of cementitious mortars. For that purpose, seven different mortars, with the same water/cement ratio but using two different brass fibres were manufactured. Not-machined brass fibres were used as a reference and compared to the waste brass fibres obtained as a by-product of wire cutting methods through electrical discharge machines. Both fibres were added to the mortars in proportions of 0.25%, 0.5% and 1% by volume of mortar. The morphology and presence of elements in the fibres were evaluated by scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). In addition, ultrasonic pulse velocity and thermal conductivity were measured to evaluate the mortar quality and the fibre dispersion into the mortar specimens. Mechanical properties were studied through flexural and compression tests. Since the fibres present a reduced length, the effect on both porosity and bulk density is negligible and the reduction on ultrasonic pulse velocity and compression strength and the slight increment on flexural strength is not remarkable due to the limited anchorage provided. Nonetheless, the improvement in the thermal conductivity of the developed mortars with recycled brass fibres, supports focusing on the niche market of heating installations, such as underfloor heating or closed-loop geothermal heat exchangers.This work has been partly financed within the European Horizon 2020 Joint Technology Initiative Shift2Rail through contract no. 826255 (IN2TRACK2). This work has also been co-financed with the project Elkartek 2019 ref. KK-2019/00023 (GOLIAT2). The authors also wish to thank the Basque Government for financial assistance through IT919-16 and IT1314-19

A parametric study on the influence of steel wool fibers in dense asphalt concrete

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Influence of encapsulated sunflower oil on the mechanical and self-healing properties of dense-graded asphalt mixtures

This paper re-evaluates the effect of sunflower oil capsules on the mechanical and self-healing properties of dense-graded asphalt mixtures. Different percentages of capsules (0.50wt.%, 0.75wt.% and 1.00wt.%) were mixed into dense asphalt. The influence of capsules on the properties of asphalt such as density, indirect tensile strength, particle loss, fatigue life, and self-healing, has been investigated. The distribution and integrity of the capsules has been also evaluated by means of CT Scans. It has been proven that capsules can survive the mixing and compaction process of asphalt mixture, do not decrease its mechanical properties and they rupture and release the oil under a high compression loading. Higher capsule content in the mixture resulted in higher oil release ratios. Furthermore, the oil released from the capsules significantly increased the self-healing capability of mixtures. Results from previous research were validated, where it had been found that 0.5% of capsules is the optimal content to obtain good mechanical performance, without affecting the rheological properties of dense-graded asphalt mixtures

Calidad, acreditación y sistemas de acreditación en salud

82 p.La calidad se ha definido como la satisfacción de las necesidades y expectativas de los clientes, teniendo como principio fundamental la continua mejora de los procesos para la entrega de un producto o servicio que satisface las necesidades del usuario. En el último tiempo se ha introducido la calidad en la atención de salud y en los procesos de atención de salud, es por esto la Organización Mundial de la Salud (OMS) la define como asegurar que el paciente pueda recibir un conjunto de servicios sanitarios para mejorar el estado de salud del paciente. Es por esto que el Ministerio de Salud debió implementar un programa de gestión de calidad asistencial con el objetivo de mejorar continuamente la entrega de servicios de salud a partir del proceso conocido como Acreditación. La Acreditación es un proceso en el cual se someten los prestadores de salud para evaluar el grado de cumplimiento respectos a estándares mínimos establecidos por cada institución. La presente revisión bibliográfica tiene como objetivo analizar los sistemas de acreditación de calidad en salud según la normativa chilena y la normativa desarrollada por la Joint Commission International. La metodología de investigación se basa en la revisión en la literatura del concepto de Calidad y Calidad Asistencial en partir de diferentes bases de datos científicas, y la revisión del concepto de acreditación según la normativa chilena en la base de datos de la Superintendencia de Salud y en la página web oficial del Sistema de Acreditación de Joint Commission International (JCI). Se concluye que la aplicación de la calidad en la salud ha generado mejoras en la atención y seguridad del paciente y el estudio de los sistemas de acreditación en Chile mostró diferencias a partir del número de estándares que se evalúan, prestadores que acredita y el proceso de evaluación