Experimental investigation and monitoring of a polypropylene-based fiber reinforced concrete road pavement

Abstract In this work, basic guidelines are provided for the design of a polypropylene-based fiber reinforced concrete (PFRC) road pavement, as applied in an actual testing section resting inside a tunnel of the "Quadrilatero Marche-Umbria" road empowerment project, Italy. Results of a six-month monitoring carried out on actual traffic loads are also presented, as a feedback to the designing stage. Monitoring encompasses direct measurement of the strain level inside the cast as well as acoustic measurement. It is shown that the fiber reinforced concrete technology provides an efficient, safe as well as cost-effective design solution for roadways, especially inside tunnels

Quinta evaluación de genotipos de espárrago en invernadero y respuesta a técnicas de envasado

El espárrago es una hortaliza perecedera, que en Argentina se requiere extender el período de oferta y optimizar su productividad y presentación, imple-mentando diferentes estrategias como la comercialización de turiones cortos y el empleo de bolsas y bandejas de IV Gama. A tal fin, se realizó un ensayo con el objetivo de evaluar el comportamiento (5º año), de los genotipos italianos Ítalo, Zeno, Eros y Ercole, versus UC-157, norteamericano, como testigo. Se estudiaron diferencias en t totales y comerciales, Nº turiones totales y comerciales y distribución de calibres y defectos encontrados (turiones espigados y cortos). Se obtuvieron 578015 turiones.ha-1 totales, siendo la producción comercial/cosecha: 59 kg.ha-1. En pos-cosecha, se evaluó la evolución del peso fresco y tres tipos de envasado: atados, bandejas y bolsas para turiones cortos. El híbrido Ítalo presentó mejor adaptación para primicia. Sobre la evolución productiva, se encontró que es posible adelantar el período de cosecha un mes comparado con la producción a campo. Además se recomienda cosechar diariamente el cultivo para evitar turiones espigados. En poscosecha se consideró la conveniencia del empleo de la técnica de IV Gama, mediante la utilización de bolsas o bandejas, para la optimización de la calidad del producto final y para extender la vida de anaquel. De esta forma se demostró la importancia de una adecuada planificación que incluye la elección criteriosa del híbrido y el acondicionamiento y presentación del producto final.Asparagus is a perishable vegetable that in Argentina requires its period of supply to be extended and the optimisation of its productivity and presentation, implementing different strategies such as the presentation of short spears (turions) and the use of bags and trays for Category IV products. To this end, the behaviour of the genotypes Ítalo, Zeno, Eros and Ercole, of Italian origin, versus UC-157, from the USA, as a control, was evaluated in the fifth year of productivity. Differences in the following characters were studied: total and commercial spear yield, number of total and commercial spears, calibre distribution and the proportion of defects observed (spiked and short spears). The following mean values were obtained: 578015 spears.ha-1, with a commercial production of 59 kg.ha-1. In postharvest, the evolution of fresh weight was evaluated, plus the influence of three types of packaging: tied bundles, trays and bags for short spears. The hybrid Ítalo demonstrated superior behaviour for primary production performance. Regarding production evolution, it was shown that it is possible to forward the harvest period by one month compared to field production. Additionally, daily harvesting is recommended in the glasshouse to avoid spiked spears. In postharvest the desirability of using bags and trays for Category IV was considered, in order to optimise the quality of the final product and to extend shelf-life. By these means, the importance of adequate planning before crop planting, including judicious choice of hybrid and the conditioning and presentation of the final product, was demonstrated.Fil: Giménez Azara C.. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Facultad de Ciencias Agrarias; ArgentinaFil: Castagnino A.M.. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Facultad de Ciencias Agrarias; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Diaz, Karina Elizabeth. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Tarantino, M.B.. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Rogers, William John. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Cientifico Tecnolológico Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología. Laboratorio de Biología Funcional y Biotecnología; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomía; Argentin

Espressioni approssimate per il Coefficiente di Invecchiamento e la Funzione di Rilassamento nell'Analisi Viscoelastica di Strutture in Calcestruzzo

Atti del Dipartimento di Ingegneria Strutturale, Politecnico di Torin

Modeling and numerical investigation of the viscoelastic behavior of laminated concrete beams strengthened by CFRP strips and carbon nanotubes

The paper aims to prove that the application of innovative constituents and materials can noticeably affect the mechanical behavior of structures. The research is focused on the long-time behavior of concrete beams reinforced by Carbon Fiber Reinforced Polymer (CFRP) strips applied on their external surfaces. The concrete and the CFRP are both characterized by time-dependent mechanical features according to the theoretical framework provided by the linear viscoelasticity. Their properties are described through the introduction of the proper creep functions. The reinforcing strips are made of a polymer matrix reinforced by straight long Carbon fibers and randomly oriented Carbon nanotubes (CNTs). Due to the presence of two reinforcing phases at different levels (nano- and micro-scale), a multiscale model is introduced to compute the global mechanical properties of these innovative composites. Their characterization at the nano-scale is accomplished through the Eshelby-Mori-Tanaka scheme, whereas the Hanh approach provides the overall engineering constants of the CFRP strips. The Timoshenko beam theory for laminated beams is employed to describe the mechanical behavior of the structures. A numerical solution is developed to achieve the time dependency of central deflections and the redistribution of stresses along the thickness of the layered structures. Several responses are investigated to show also the effect of the mass fraction of CNTs, the thickness and the number of CFRP strips. The results presented in this paper could be taken into account to improve the structural response of concrete beams in contrasting the creep phenomenon due to the intrinsic nature of the material