Mechanical performance of roller compacted concrete with recycled concrete aggregates

Because the recycling of construction and demolition waste (CDW) has been deemed to be a priority, the use of a recycled aggregate has been widely demonstrated as a sustainable contribution among different materials applied in civil projects. Roller compacted concrete applications (RCC) offer technical, economic and ecological solutions in many civil construction projects. To the best of the authors’ knowledge, there has been little research on the use of RCC with a coarse recycled aggregate that does not originate from pavement. This research evaluates the use of recycled concrete aggregates (RCA) from a CDW recycling plant in RCC mixtures. Four series of RCC mixtures were produced with different cement contents (110, 175, 250 and 350 kg/m3). Each series consisted of three mixtures with different RCA incorporation ratios (0%, 50% and 100%) of natural coarse aggregates, thus producing 12 RCC mixtures to evaluate the effect on the compaction, the mechanical and physical properties while highlighting a new laboratory casting method for flexural strength and drying shrinkage tests. Based on the obtained results, the use of coarse RCA in RCC production is feasible at a replacement level of 100% when using these materials in road pavement bases

Effect of Processed Volcanic Ash as Active Mineral Addition for Cement Manufacture

In the last quarter of 2021, there was a very significant eruption of the Cumbre Vieja volcano on the island of La Palma, belonging to the Canary Islands, Spain. It generated a large amount of pyroclastic volcanic materials, which must be studied for their possible applicability. This work studies the properties and applicability of the lava and volcanic ash generated in this process. The need for reconstruction of the areas of the island that suffered from this environmental catastrophe is considered in this study from the point of view of the valuation of the waste generated. For this purpose, the possibility of using the fine fraction of ashes and lava as a supplementary cement material (SCM) in the manufacture of cement is investigated. The volcanic material showed a chemical composition and atomic structure suitable for replacing clinker in the manufacture of Portland cement. In this study, the cementing and pozzolanic reaction characteristics of unprocessed volcanic materials and those processed by crushing procedures are analysed. To evaluate the cementitious potential by analysing the mechanical behaviour, a comparison with other types of mineral additions (fly ash, silica fume, and limestone filler) commonly used in cement manufacture or previously studied was carried out. The results of this study show that volcanic materials are feasible to be used in the manufacture of cement, with up to a 22% increase in pozzolanicity from 28 to 90 days, showing the high potential as a long-term supplementary cementitious material in cement manufacturing, though it is necessary to carry out crushing processes that improve their pozzolanic behaviour

Geranium's response to compost based substrates

8 páginas, 2 figuras, 3 tablas, 10 referencias.-- International Symposium on Composting and use of Composted Materials for Horticulture, celebrado del 5-11 de abril 1997, en Ayr, Scotland, United Kingdom.The effects of compost based substrates on growth and nutrition of geranium (Pelargonium zonale cv Lucky Break F2) were investigated. Substrates of manure compost, cotton gin trash compost, municipal solid waste compost and pine bark utilized as potting media for domestic use, produced an underdevelopment of geranium plants with respect to the control. This behaviour is related to the inferior physical properties of the compost-based potting media, nitro gen immobilization due to the high C/N ratio of pine bark, and probably lack of available phosphorus originated by high calcium and high pH of the compost-based media. Nitrogen fertilization and a longer period of cultivation diminished the differences between plants grown in the control and in compost-based media. Plants grown in compost mixtures which were rich in K showed K and Ca leaf contents closer to the optimum range than did control plants.This work was supported by the Agencia de Medio Ambiente of the Junta de Andalucía and by Fertilizantes Orgánicos Melguizo, S. L.Peer reviewe

La importancia de enseñar Ciencias Sociales al estudiante en la actualidad

Reflexionar nos convence de que la excelencia está dentro de cada ser humano. La historia nos demuestra que un ser humano hambriento es capaz de matar, pero por el deseo de obtener reconocimiento es capaz de morir tal como sucedió con los apóstoles o con los millones de hindúes que supieron imponer la resistencia pacífica. Trasladando esto a la importancia de enseñar las Ciencias Sociales al estudiante en la actualidad es rescatar los hechos de pasado, asumir una conciencia social de nuestro entorno, valorar nuestra cultura y saber que no existen países pobres sino gobiernos improvisados o regiones sin oportunidades sino dirigentes sociales con oportunismos políticos y sin visión progresista, frente a lo cual el quehacer educativo de los docentes de esta área tienen la potestad de despertar el compromiso de una mente más democrática, valorativa y apreciativa del “Lugar Natal” estudiando sus aspectos geográficos, histórico – temporales, sus símbolos, su gente, su folklor, cultura, leyes y todo el quehacer social para dar paso a una revolución que incite al cambio y a una mentalidad emprendedora y de bien por los suyos. Es por ello que con el surgimiento de las metodologías activas de aprendizaje y las TIC, las Ciencias Sociales, deben considerarse importantes en la educación de los niños y jóvenes ya que lasmismas promuevenla cultura generalque contribuyenacomprenderlosfundamentos de nuestra nacionalidad, la democracia y el desarrollo del pensamiento racional y crítico – reflexivo que aportan al desarrollo de capacidades cognitivas y afectivas exigidas en las sociedades complejas, plurales y cambiante de la actualidad. PALABRAS CLAVE: Ciencias Sociales; experiencias educativas; didáctica de las Ciencias Sociales. The importance of teaching social sciences to the student today ABSTRACT Reflecting convinces us that excellence is within every human being. History shows us that a hungry human being is capable of killing, but because of the desire to gain recognition, he is capable of dying just as happened with the apostles or with the millions of Hindus who knew how to impose peaceful resistance. Translating this to the importance of teaching Social Sciences to the student today is to rescue the facts of the past, assume a social awareness of our environment, value our culture and know that there are no poor countries but improvised governments or regions without opportunities but social leaders. with political opportunisms and without a progressive vision, in the face of which the educational work of the teachers in this area has the power to awaken the commitment of a more democratic, evaluative and appreciative mind of the "Birthplace" by studying its geographical, historical -temporal aspects. , its symbols, its people, its folklore, culture, laws and all the social work to give way to a revolution that encourages change and an entrepreneurial mentality and good for their own. That is why with the emergence of active learning methodologies and ICT, Social Sciences, should be considered important in the education of children and young people since they promote the general culture that contribute to understanding the foundations of our nationality, democracy and the development of rational and critical-reflective thinking that contribute to the development of cognitive and affective capacities required in today's complex, plural and changing societies. KEYWORDS: social Sciences; educational experiences; Teaching social sciences

Nitrogen mineralization in soils amended with organic by-products of olive oil and sugarbeet processing industries

Mineralization of organic-N supplied te two different types of soils by an alpechín (olive-oil mill waste water)-compost and a beet vinasse after three consecutive years was studied. Results were compared with those obtained for a mineral fertilizer treatment and a control (unfertilized). N-mineralization can be described by a first order kinetic model. Both organic residues produced an important increase in me organic-N loading of the soils which is slowly released over a time.Peer Reviewe

Alkali-Activated Stainless Steel Slag as a Cementitious Material in the Manufacture of Self-Compacting Concrete

This work develops the manufacture of self-compacting concrete (SCC) with 50% cement reduction. As an alternative binder to cement, the viability of using an alkali-activated combination of stainless steel slag (SSS) and fly ash (FA) has been demonstrated. SSS was processed applying three different treatments. Binders were manufactured mixing 35% SSS with 65% FA, as precursors, and a hydroxide activating solution. This binder was replaced by the 50% cement for the manufacture of SCC. The results obtained show good mechanical properties and durability. The study shows a reduction in the use of cement in the manufacture of SCC reusing two wastes

Mimicking the extracellular matrix – a biomaterials approach to inhibit tissue fibrosis

Epithelial tissue is marked by the presence of a specialized, highly cross-linked, sheet-like extracellular matrix, the basement membrane. Tissue-invasive events, such as the epithelial-to-mesenchymal transition (EMT) - a key event in gastrulation, tissue fibrosis and cancer metastasis – are characterized by irreversible structural changes of the basement membrane through proteolytic processing by matrix metalloproteinases (MMPs). We have recently reported a previously unidentified laminin fragment that is released during EMT by MMP2 and that modulates key EMT-signalling pathways. Specifically, interaction of the laminin fragment with α3β1-integrin triggers the down-regulation of MMP2 expression, thereby constituting a cell-basement membrane-cell feedback mechanism. Inhibiting MMPs has been proposed as a strategy to prevent pathological cell migration and basement membrane breakdown in the course of EMT. Here, we explore this cell-matrix-cell feedback mechanism to target pathological EMT in the course of tissue fibrosis. We present an electrospun biomaterial that is functionalized with the recombinant laminin fragment and that can be directly interfaced with epithelial tissue to interfere with EMT pathways and inhibit MMP2 expression and activity in vitro and in vivo. We demonstrate how interaction of the functionalized synthetic membrane with peritoneal tissue inhibits mesothelial EMT in a mouse model of TGFβ-induced peritoneal fibrosis by decreasing active MMP2 levels, and propose a mechanism of how the laminin fragment acts downstream of α3β1-integrin in epithelial cells, after it is released from the basement membrane

Eco-Efficient Cement-Based Materials Using Biomass Bottom Ash: A Review

In recent years the use of biomass for electricity generation in thermal and cogeneration plants has increased worldwide because it is an environmentally clean fuel whose impact measured in greenhouse gas emissions is practically zero. However, biomass bottom ash, a waste produced during combustion, has also increased considerably, which has both a negative economic and environmental impact, due to landfill transport and management of this by-product. Although biomass bottom ash has potential characteristics for application in the manufacture of construction materials, its full-scale application is difficult because of the wide range in physicochemical properties, depending on the type of biomass burned, such as wood residue, olive waste, waste paper sludge, cocoa shell, etc., and the type of combustion process in the plant. This study reviews the influence on the physicochemical properties, mechanical behavior, and durability of different cement-based materials, such as mortars, concrete, and cement-treated granular material, manufactured from biomass bottom ash. The previous studies demonstrate the feasibility of substituting natural materials for biomass bottom ash in cement-based materials, presenting adequate mechanical behavior and durability properties to comply with the required technical specifications in different building materials

Considerations on the low-pressure exhaust gas recirculation system control in turbocharged diesel engines

Although high-pressure exhaust gas recirculation has been commonly used in turbocharged diesel engines for controlling the NOx formation, recent advances in after-treatment and material technology make possible using a low-pressure architecture, which recirculates the exhaust gas upstream the compressor. This brief article presents a basic study of control aspect related to the low-pressure architecture, emphasising the similarities and differences with the highpressure system. Data from experimental tests with both configurations and from a one-dimensional wave action model simulations are combined for the analysis of the input–output paring, linearity and the transient performance of both systems.This research has been partially financed by the Spanish Ministerio de Economia y Competitividad, through project IPT-370000-2010-022 'Investigacion y desarrollo de tecnologias de EGR adaptadas a las nuevas arquitecturas y requerimientos de refrigeracion en motores diesel sobrealimentados para automocion (HIREFIRE)'.Lujan Martinez, JM.; Guardiola García, C.; Plá Moreno, B.; Cabrera López, P. (2014). Considerations on the low-pressure exhaust gas recirculation system control in turbocharged diesel engines. International Journal of Engine Research. 15(2):250-260. https://doi.org/10.1177/1468087413485209S25026015