Mix design and properties assessment of Ultra-High-Performance Fibre Reinforced Concrete (UHPFRC)

日本には約110種の蚊が産する。その中で医学的に重要なのは, 幼虫(ボウフラ)が人里近くの水域に発生し, 雌成虫がヒトから好んで吸血する種である。西日本ではアカイエカ(南西諸島ではネッタイイエカにおきかわる), チカイエカ, コガタアカイエカ, ヒトスジシマカなどが最も重要である。これらの種は生態がことなるので, その被害に対する効果的対策もことなる。雌成虫が吸血源となる動物を発見して完了するまでの過程は複雑で, わかつていない点もある。

Biology of mosquitoes.

This paper addresses the development of an eco-friendly Ultra-High Performance Concrete (UHPC) with efficient cement and mineral admixtures uses are investigated. The modified Andreasen & Andersen particle packing model is utilized to achieve a densely compacted cementitious matrix. Fly ash (FA), ground granulated blast-furnace slag (GGBS) and limestone powder (LP) are used to replace cement, and their effects on the properties of the designed UHPC are analyzed. The results show that the influence of FA, GGBS or LP on the early hydration kinetics of the UHPC is very similar during the initial five days, while the hydration rate of the blends with GGBS is mostly accelerated afterwards. Moreover, the mechanical properties of the mixture with GGBS are superior, compared to that with FA or LP at both 28 and 91 days. Due to the very low water amount and relatively large superplasticizer dosage in UHPC, the pozzolanic reaction of FA is significantly retarded. Additionally, the calculations of the embedded CO2 emission demonstrate that the cement and mineral admixtures are efficiently used in the developed UHPC, which reduce its environmental impact compared to other UHPCs found in the literature.

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Development of an eco-friendly Ultra-High Performance Concrete (UHPC) with efficient cement and mineral admixtures uses

https://pure.tue.nl/ws/files/3881873/448899096909189.pdf

Effect of nano-silica on the hydration and microstructure development of Ultra-High Performance Concrete (UHPC) with a low binder amount

The effect of activator concentration on the residual strength of alkali-activated fly ash pastes subjected to thermal load

Microstructural changes of an OPC cement paste after being exposed at various elevated temperatures and further rehydration have been evaluated using 29Si MAS-NMR. Thermogravimetry and XRD are also employed to complement the information. NMR studies of cement paste exposed to high temperatures demonstrate a progressive transformation of C-S-H gel that leads at 450°C, to a modified C-S-H gel. For temperatures above 200°C to a progressive formation of a new nesosilicate. At 750°C, the transformation of C-S-H is complete into the nesosilicate form with a C2S stoichiometry close to larnite, but less crystalline. Also is observed an increase of portlandite that takes place up to temperatures of 200°C. A progressive increase of calcite formation up to 450°C is noticed. The ettringite disappearance below 100°C is confirmed and the portlandite and calcite are converted to lime at 750°C. The initial anhydrous phases as larnite and brownmillerite remain unaltered during heating. Rehydration of the heated samples (450 and 750°C) shows recrystallization of calcite, portlandite and ettringite, and the C-S-H reformation from the new nesosilicate. The larnite and brownmillerite remain unaltered during rehydration. The developing of damaged due to the formation of microcracking is detected and improved because of rehydration phenomena.

Dehydration and rehydration processes of cement paste exposed to high temperature environments

INTRODUCTION: Water tanks placed on the ground are an important drinking water container at home; however, Aedes aegypti is very frequently colonizing this kind of reservoirs in an urban health area of Camaguey province, Cuba. OBJECTIVES: to determine the entomological contribution of these water tanks –widely distributed containers at community settingto infestation by Aedes aegypti in an urban health area of Camaguey province. METHODS: Out of the total number of containers positive to Aedes aegypty, the amount of water tanks involved was estimated, in order to determine the specific container rate (sCR) together with the average of pupas per positive water tank on the ground. These tanks were characterized during the study of the house using an application form prepared to this end. Similarly, the average total number of hours that the tanks remained uncovered was estimated. RESULTS: It was found that 36.03 % of all positive containers were water tanks on the ground, which were mostly filled with water from the aqueduct outdoors; being the sCR=2,69. Over 97 % of them had faulty covers whereas 92.5 % remained uncovered for 6 or 7 hours a day. Seventeen positive tanks sheltered 41 pupas for an average of 2.41 pupas per tank. CONCLUSIONS: The contribution of water tanks on the ground to the presence of Aedes aegypti pupas in the area makes it necessary to give priority to the inspection and surveillance of such containers on the part of the population and the expert staff. The supply of new covers will not represent the final solution to this problem if the behaviour of the dwellers in a house does not change. It is required to improve the information to be provided to the population so that the risk perception is changed and the level of knowledge on this topic is raised. In this way, it will be possible to involve the community more actively in this process as a key element to make it really sustainable.

Aedes (St.) aegypti en tanques bajos y sus implicaciones para el control del dengue en Camagüey

Se reporta la presencia de Stegomyia aegypti, importante vector del dengue/dengue hemorragico en un deposito raro, una zanja con vertimiento de aguas negras extremadamente poluida. Este hallazgo al parecer es el resultado de condicionantes desfavorable en el interior de las viviendas debido a las intensas y extensivas jornadas de tratamiento focal y adulticida ejecutadas en todo el universo urbano atendido por el policlinico. Por ello se deben extremar tambien las acciones de pesquisaje para detectar y destruir todo probable sitio de cria de mosquitos en el peridomicilio, implementar acciones de lucha integrada que incluyan biologicas, fisicas, quimicas y educativas segun lo requiera para establecer barreras higienico-epidemiologicas que impidan la presencia y dispersion de la especie en el territorio.

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Zanja de aguas negras como criadero de Stegomyia aegypti: Aspecto entomológico a considerar en el control de la especie

Introduction: dengue and yellow fever, two Aedes aegypti-borne life-threatening tropical diseases, are currently showing an alarming (re)emergence. Objective: to discuss the urgent need of community involvement in counterchecking dengue fever, considering the Aedes aegypti occurrence in Camaguey province. Methods: a retrospective-descriptive study was conducted through the review of sampling records of three health care areas of Camaguey, during the OctoberDecember 2011 quarter. Larval and adult insect collection was performed following Cuba's National Vector Control Network guidelines by checking the inside and surrounding areas of urban houses in 22-day cycles, during which samples were kept in vials containing 70% alcohol and then labeled with their corresponding breeding site data. Results: out of the 31 types of containers that tested positive for the vector, the minority amounting to 38.70 %, was made up of permanent, usable and unmodifiable containers. However, among them were included 74.37 % of containers that had tested positive, which indicates that local families must give them top priority in terms of their adequate surveillance and management. Conclusions: considering the relevant role of permanent, usable and nonmodifiable containers in the human-induced risk of Aedes aegypti breeding in three health care areas of Camaguey province, there is a pressing need for community involvement in the surveillance and control of such containers so as to have a real impact on the dengue prevention process.

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La impostergable participación comunitaria en la lucha contra el dengue

Se reporto para el Departamento del Peten (region norte de Guatemala), la presencia de 33 especies de culicidos, pertenecientes a 16 generos, como resultado de las prospecciones entomologicas realizadas entre 1999-2001. La distribucion no resulto ser homogenea en todo el territorio, siendo los mas abundantes en especies y de mejor dispersion, el genero Culex y Anopheles, respectivamente. El area de salud Peten Norte, aporto la mayor variedad de culicidos durante el estudio con 93,9 % del total reportado. Varios de los insectos capturados tienen una gran relevancia sanitaria, pues intervienen en la transmision de importantes enfermedades al hombre, siendo para la region norte guatemalteca, la malaria la de mayor incidencia, observandose tambien un incremento notable en la dispersion de Stegomyia aegypti hacia ambientes no tan urbanizados. Las causales que estan determinando la presencia y distribucion de la familia Culicidae en el Departamento del Peten, seran objeto de analisis en futuras investigaciones.

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Lorenzo Diéguez Fernández

Papers

Dehydration and rehydration processes of cement paste exposed to high temperature environments

Aedes (St.) aegypti en tanques bajos y sus implicaciones para el control del dengue en Camagüey

Zanja de aguas negras como criadero de Stegomyia aegypti: Aspecto entomológico a considerar en el control de la especie

La impostergable participación comunitaria en la lucha contra el dengue

Contribución al estudio de la familia Culicidae de Guatemala: relación y distribución geográfica de las principales especies en la región norte