Deflection control for reinforced recycled aggregate concrete beams: Experimental database and extension of the fib Model Code 2010 model

Recycled aggregate concrete (RAC) has emerged as a viable solution for solving some of the environmental problems of concrete production. However, design guidelines for deflection control of reinforced RAC members have not yet been proposed. This study presents a comprehensive analysis of the applicability of the fib Model Code 2010 (MC2010) deflection control model to reinforced RAC beams. Three databases of long-term studies on natural aggregate concrete (NAC) and RAC beams were compiled and meta-analyses of deflection predictions by MC2010 were performed. First, the MC2010 deflection control model was tested against a large database of long-term tests on NAC beams. Second, a database of RAC and companion NAC beams was compiled and initial and long-term deflections were calculated using the MC2010 model. It was shown that deflections of RAC beams are significantly underestimated relative to NAC beams. Previously proposed modifications for MC2010 equations for shrinkage strain and creep coefficient were used, and new modifications for the modulus of elasticity and empirical coefficient β were proposed. The improved MC2010 deflection control model on RAC beams was shown to have equal performance to that on companion NAC beams. The proposals presented in this paper can help engineers to more reliably perform deflection control of reinforced RAC members.This is the peer-reviewed version of the article: N. Tošić, S. Marinković, and J. de Brito, ‘Deflection control for reinforced recycled aggregate concrete beams: Experimental database and extension of the fib Model Code 2010 model’, Structural Concrete, vol. 20, no. 6, pp. 2015–2029, 2019 [https://doi.org/10.1002/suco.201900035

An attempt to control natural focus of leptospirosis grippotyphosa by rodenticide - a long-term study [1977-2004]

The purpose of the study was to suppress a known natural focus of fi eld fever exerting an infl uence on animal hosts of leptospires – small terrestrial mammals (s.t.m.) by rodenticide. After repeated application of the zinc phosphide rodenticide, the s.t.m. were regularly live-trapped and checked for leptospirosis by dark-fi eld microscopy and culture of their renal tissue and serological examination. Isolated leptospira strains were typed by help of rabbit factor sera. The deratization infl uenced the s.t.m. structure considerably: the proportion of the dominant Microtus arvalis subjects – the main reservoirs of Leptospira kirschneri serovar Grippotyphosa – were gradually and substantionally reduced and, contrarily, the percentage of the potetial hosts subjects – Clethrionomys glareolus and Apodemus fl avicollis – rose decisively over time. Changes in culture and serological positivity for leptospirosis of s.t.m. have also been enregistered. The highest original infestation of M. arvalis have slowly but strongly decreased while that of C. glareolus and A. fl avicollis has increased decisively and reached its maximum within the last years of investigation. It is probable that these two animal species have undertaken the leading role in the maintenance of the natural focus of the fi eld fever. In other animal species analogous trends were not registered. Based on these long-term fi ndings, there exists the possibility to suppress only partially and temporarily the epizootic process of leptospirosis in a natural focus that can be desirable in some circumstances (building or free time activities, etc.)

Utility of phylogenetic studies in the identification of Leptospira strains

A phylogenetic tree, which distinguishes between the serovars and serogroups of leptospires common in Central Europe was constructed using an established RAPD procedure together with digital reading and evaluation (using different computer software programs) of the generated amplified DNA patterns. The application of this procedure has revealed a consistent correspondence between serogroup and genotype (position in constructed tree) in 69 cases, and serovar and genotype in 72 cases, of wild strains of leptospires. There was an agreement between serovar and genotype in cases of strains of Grippotyphosa, Pomona, Mozdok, Arborea and Sorexjalna as well as between serogroup and genotype in cases of Australis, Bataviae and Sejroe. With the procedure used in this study, it was not possible to distinguish between reference strains of serovars Jalna, Bratislava and Lora (all serogroup Australis) as well as between serovars Icterohaemorrhagiae and Copenhageni (both of serogroup Icterohaemorrhagiae). In contrast to this, wild strains belonging to serogroup Sejroe were distributed between Polonica, Istrica, Saxkoebing and Sejroe serovars. Endemic strains of leptospires tested, were also distinguishable

Diagnóstico da geração e da composição dos RCD de Fortaleza/CE Generation and composition diagnosis of C&D waste of Fortaleza/CE

Este trabalho objetivou apresentar os resultados de um diagnóstico anual da geração e da composição dos resíduos de construção e demolição de Fortaleza. Durante 12 meses, foram colhidas informações das empresas coletoras e da prefeitura, tais como a quantidade e o preço do metro cúbico do entulho coletado e o destino dado a ele. Foram ainda coletadas amostras de resíduos de construção e demolição nos locais de descarte licenciados pela prefeitura. Os resultados apontam que os locais licenciados recebem em média 702 toneladas.dia-1, sendo que a composição desses resíduos de construção e demolição é, em média, de 65% de restos de argamassa, concreto e material cerâmico. Constatou-se também que grande parte desse tipo de resíduo é descartado ilegalmente, sendo que os dois principais aterros irregulares somam uma área aproximada de 26 hectares. Estima-se que esse sistema movimenta R$4,5 milhões anualmente e que quase metade desse montante é aportado somente pela Prefeitura Municipal.<br>This article aimed to present the results of an annual diagnosis of generation and composition of Fortaleza’s construction and demolition waste. During 12 months CDW collection companies’ and the city hall’ information were researched, such as the amount and the price of the cubic meter of the collected wastes and the destiny given to them. Samples of construction and demolition waste were either collected at the licensed disposal places. The results point that licensed places receive 702 tons.day-1, on average, and the composition of this construction and demolition waste is made, on average, by 65$4.5 million annually and almost half of this amount is paid only by the Municipal City hall