Fuel Spray Diagnostics

Fundamental experimental data base for turbulent flow mixing models is provided and better prediction of the more complex turbulent chemical reacting flows. Analytical application to combustor design is provided and a better fundamental understanding of the combustion process

Carbonation of concrete with construction and demolition waste based recycled aggregates and cement with recycled content

Durability is a major concern in concrete (particularly recycled concrete) structures exposed to carbonation-induced corrosion, given the social, economic, environmental and safety implications involved. This article explores carbonation performance in concrete with 25% or 50% mixed recycled construction and demolition waste aggregate, alone or in conjunction with cement containing 25% fired clay construction and demolition waste. Irrespective of cement type, the mean carbonation depth was slightly greater in materials with 25% or 50% recycled aggregate than in concretes with 100% natural aggregate, although the difference was not statistically significant for the 25% replacement ratio. In all the concretes studied, the carbonation coefficient was below the 4 mm/yr0.5 indicative of good quality. Based on the prediction model proposed in Spain’s concrete code, reinforcement passivity was guaranteed in all these types of concrete when exposed to class XC1 to XC4 carbonation environments for substantially longer than their 100 year design service life.This study was funded under research projects BIA 2013-48876-C3-1-R, BIA2013-48876-C3-2-R and BIA2016-76643-C3-1-R awarded by the Ministry of Science and Innovation and grant GR 18122 awarded to the MATERIA Research Group by the Regional Government of Extremadura and the European Regional Development Fund, ERDF. In 2016 University of Extremadura teaching and research personnel benefitted from a mobility grant (MOV15A029) awarded by the Regional Government of Extremadura and in 2018 from a José Castillejo (CAS17/00313) scholarship granted by the Spanish Ministry of Education, Culture and Sport. Philip Van den Heede is since October 2017 a postdoctoral fellow of the Research Foundation—Flanders (FWO) (project number 3E013917) and acknowledges its support.Peer reviewe

Design and simulation of metropolitan urban growth demands scenarios

La generación y simulación de escenarios exploratorios externos es un instrumento útil en los procesos de planificación y toma de decisiones, de especial relevancia en el ámbito territorial y metropolitano (Peterson et al, 2003; Pettit y Pullar, 2004; Luca, 2007; Carsjens, 2009), cuyo calado en el proceso de planificación en España es escaso hasta la fecha (Valenzuela, Aguilera, Soria y Molero, 2008). En este artículo se presenta un modelo basado en Dinámica de Sistemas para estimar las demandas de nuevo suelo urbano en ámbitos metropolitanos. El modelo se ha desarrollado concretamente para dos ámbitos metropolitanos españoles (Región Urbana de Madrid y Aglomeración Urbana de Granada) para los cuales se ha realizado un proceso de calibración individual, Una vez calibrado el modelo para dichos ámbitos, y a través del planteamiento de tres escenarios futuros, se han simulado las posibles tendencias de las demandas de ocupación urbana que podrían derivarse de las premisas establecidas en cada escenario, con unos resultados satisfactorios. Dichos resultados podrán ser empleados en otros trabajos que permitirán localizar espacialmente, mediante modelos de simulación espacial, las demandas estimadas, para mostrar y evaluar posibles consecuencias espaciales y territoriales de los procesos de crecimiento metropolitano.The design and development of future explorative external scenarios are useful tools for the spatial planning and even more for the metropolitan planning (Peterson et al, 2003; Pettit y Pullar, 2004; Luca, 2007; Carsjens, 2009). However, spatial planning policy and practices in Spain lack of this instruments (Valenzuela, Aguilera, Soria y Molero, 2008) This paper shows a System Dynamics-based model designed to estimate urban growth demands in metropolitan areas. This model has been specifically developed for Madrid and Granada metropolitan areas (Spain), where the model has been calibrated. After the calibration, three future urban growth demands scenarios has been designed and simulated using the model developed. The urban growth demands obtained may be used in later research to spatially locate that demands using spatial simulation models.Peer Reviewe

Assessment of the permeability to aggressive agents of concrete with recycled cement and mixed recycled aggregate

[Abstract:] Acceptance by the construction industry of recycled concrete as a sustainable alternative material is contingent upon a reliable assessment of its permeability to corrosive agents. This study analyses the transport mechanisms associated with chloride (Cl−), oxygen (O2) and carbon dioxide (CO2) ions in concrete with cement made with 10% or 25% ground recycled concrete (GRC) separately or in combination with 50% mixed recycled aggregate (MRA). The findings show that, irrespective of aggregate type, concrete with GRC exhibited lower resistance to ingress than conventional concrete due to its greater porosity. Nonetheless, O2 permeability was consistently below 4.5 × 10−17 m2 and CO2 penetration, under 4 mm/year0.5, indicative of concrete with high quality. Resistance to CO2 and Cl− penetration in the materials with 10% GRC was similar to the values observed in conventional concrete. On the other hand, the incorporation of 25% GRC increased the penetration of CO2 and Cl- by 106% and 38%, respectively. Further to those findings in normal carbonation environments, reinforcement passivity would be guaranteed in such recycled materials over a 100 year service life.This study benefitted from the Spanish Ministry of Science, Innovation and Universities mobility grant ETS18/00313, awarded in connection with pre-doctoral university professor scholarship 16/02693, under which Blas Cantero conducted research at the Lisbon University Instituto Superior Técnico construction laboratory. European Regional Development Fund (ERDF) funding was also received for an Interreg-POCTEP research grant (0008_ECO2CIR_4_E, ‘Project for cross-border cooperation to introduce the eco- and circular economy by reducing waste generation and enhancing waste recycling, management and valorisation in Central Spain, Extremadura and Alentejo) and, in conjunction with the Government of Extremadura, under grant GR 18122, awarded to the MATERIA research group. The support of the Foundation for Science and Technology, Civil Engineering Research and Innovation for Sustainability (CERIS) research centre and Instituto Superior Técnico is also acknowledged.Interreg-POCTEP; 0008_ECO2CIR_4_EJunta de Extremadura; GR 1812

Thermal performance of concrete with recycled concrete powder as partial cement replacement and recycled CDW aggregate

[Abstract:] This novel study was triggered by a lack in the international literature of the simultaneous use of ground recycled concrete (GRC) as a cement replacement and mixed recycled aggregate as part of the granular skeleton in recycled concrete. It explores the thermal behaviour of concrete mixes bearing 10 wt% or 25 wt% GRC as a cement replacement and 25 wt% or 50 wt% mixed recycled aggregate (MRA) sourced from construction and demolition waste (CDW). The experimental programme conducted assessed concrete’s dry density, open porosity, electrical and thermal conductivity and specific heat capacity. The findings showed that the use of 10% and 25% GRC, in conjunction with 50% MRA, reduced thermal conductivity by 7.9% to 11.8% and raised specific heat capacity by 6.0% to 9.1% relative to concrete with 100% natural aggregate (NA). A cross-property analysis revealed that improved thermal performance was linearly related to lower density and higher porosity. The results also support the conclusion that these new recycled aggregate concrete mixes are more energy-efficient construction materials than conventional concrete.This research was funded by Spanish Ministry of Science, Innovation and Universities mobility grant ETS18/00313, awarded in connection with pre-doctoral university professor scholarship 16/02693, under which Blas Cantero conducted research at the Lisbon University Instituto Superior Técnico construction laboratory. European Regional Development Fund (ERDF) funding was also received for an Interreg-POCTEP research grant (0008_ECO2CIR_4_E, ‘Project for cross-border cooperation to introduce the eco- and circular economy by reducing waste generation and enhancing waste recycling, management and valorisation in Central Spain, Extremadura and Alentejo) and, in conjunction with the Government of Extremadura, under grant GR 18,122 awarded to the MATERIA research group.Interreg-POCTEP; 0008_ECO2CIR_4_EJunta de Extremadura; GR 1812

Industrial Low-Clinker Precast Elements Using Recycled Aggregates

ABSTRACT: ncreasing amounts of sustainable concretes are being used as society becomes more aware of the environment. This paper attempts to evaluate the properties of precast concrete elements formed with recycled coarse aggregate and low clinker content cement using recycled additions. To this end, six different mix proportions were characterized: a reference concrete; 2 concretes with 25%wt. and 50%wt. substitution of coarse aggregate made using mixed construction and demolition wastes; and others with recycled cement with low clinker content. The compressive strength, the elastic modulus, and the durability indicator decrease with the proportions of recycled aggregate replacing aggregate, and it is accentuated with the incorporation of recycled cement. However, all the precast elements tested show good performance with slight reduction in the mechanical properties. To confirm the appropriate behaviour of New Jersey precast barriers, a test that simulated the impact of a vehicle was carried out.This research was funded by SODERCAN, S.A. (SODERCAN/FEDER) and BIA2013-48876-C3-2-R awarded by the Ministry of Science and Innovation

Enhancement of mechanical and thermoelectric properties of Ca3Co4O9 by Ag addition

Ca3Co4O9 + x wt.% Ag (x = 0, 1, 3, 5, and 10) polycrystalline thermoelectric ceramics have been prepared by a sol–gel route via nitrates followed by high temperature treatment before sintering. Out-of-plane XRD data have shown that major phase is the Ca3Co4O9 one, accompanied by metallic Ag. SEM observations have agreed with the XRD data. Apparent density measurements have revealed that all samples possess densities ranging between 80% and 90% when Ag content is raised. Mechanical properties have shown a drastic increase of bending stress when Ag is added to the samples. Electrical resistivity decreases with the Ag content, compared with the pure ones, while Seebeck coefficient slightly decreases. Maximum power factor values around 0.43 mW/K2 m at 800 °C have been achieved for the 10 wt.% Ag samples which is much higher than the measured in the pure Ca3Co4O9 samples.This research has been supported by MINECO-FEDER (MAT2013-46505-C3-1-R). The authors wish to thank the Gobierno de Aragón-Fondo Social Europeo (Consolidated Research Groups T12 and T87) for financial support.Peer Reviewe

Mapping the Probability of Schistosomiasis and Associated Uncertainty, West Africa

We aimed to map the probability of Schistosoma haematobium infection being >50%, a threshold for annual mass praziquantel distribution. Parasitologic surveys were conducted in Burkina Faso, Mali, and Niger, 2004–2006, and predictions were made by using Bayesian geostatistical models. Clusters with >50% probability of having >50% prevalence were delineated in each country

Bionomics of Mussidia nigrivenella (Lepidoptera: Pyralidae) on three host plants

Life table studies of Mussidia nigrivenella Ragonot, a pest of maize in Benin, showed that host plant species had a significant effect on larval survival and developmental time. The maximum percentage of larvae surviving was recorded on jackbean, Canavalia ensiformis (36%) and lowest on maize (18%). Mean developmental time for larvae was longest on maize (19.8 days) and shortest on jackbean (17.2 days). The number of eggs laid was highest for females from larvae fed on jackbean (x̄ = 176), followed by velvetbean, Mucuna pruriens (x̄ = 143), and lowest for females where larvae had fed on maize (x̄ = 127). Longevity of ovipositing females was higher on jackbean (5.4 days) than of those from any other host plants. According to the growth index and life table statistics, jackbean was the most suitable host plant, followed by velvetbean, and maize, the least suitable. Thus, jackbeans should be recommended for use in mass rearing programmes of M. nigrivenella, e.g. as a host for parasitoids in future biological control programmes. Because of the high suitability of jack- and velvetbeans for M. nigrivenella, planting of these increasingly important cover crops should be timed in such a manner that the emergence of female moths from mature pods does not coincide with maize plants in a suitable developmental stage for oviposition and development of young M. nigrivenella larvae