1,721,026 research outputs found
Orti Botanici storici e di nuova o recente istituzione in Italia: ruoli attuali, attività e impegni per il futuro
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Experimental analysis of time dependent phenomena and temperature effects on macro-synthetic fibre reinforced concretes in different loading conditions
Full text linkFibre reinforced concretes (FRCs) are composite materials now largely adopted in structural applications given their mechanical properties in terms of the residual tensile strength, almost absent for plain concrete. The short-term mechanical behaviour of these material has been deeply studied, while their time-dependent deformations have received less attention from the scientific community. The present paper presents the experimental characterization of the creep deformations of a concrete reinforced with polypropylene fibers by means of different types of tests, together with an analysis of the temperature effect. Innovative test set-ups are used to this aim. The paper presents the results of shrinkage, compression creep, uniaxial tension and flexural creep tests and discusses the contribution of the different components of the FRC to the composite creep behavior
Experimental Investigation on the Influence of Temperature Variations on Macro-synthetic Fibre Reinforced Concrete Short and Long Term Behaviour
No full textIn the last decades, fibre reinforced concretes became widely adopted in structural applications. Nevertheless, some elements of their mechanical behaviour are not fully understood. For instance, the effect of environmental conditions on the short and long-term behaviour of these materials has been studied to a limited extent only. In this perspective, the present paper presents the results of a large experimental campaign involving flexural tests on Macro Synthetic Fibre Reinforced Concrete (MSFRC) specimens under short- and long-term loads. Two different polypropylene Fibres were used, with dosages of 8 kg/m3 and 10 kg/m3. The effect of temperature on the short-term behaviour of these materials was investigated by performing three-point bending tests at 20 °C and 40 °C in cracked and uncracked conditions. The effect of temperature variations on long-term deformations was studied by means of four-point bending tests on pre-cracked notched beams at increasing temperatures, from 20 °C to 40 °C. The paper presents the test results as well as analyses the effective number of fibres crossing the cracks
Influence of moderate temperature variation on fibers for MSFRCs
No full textFibre reinforced concretes are nowadays widely adopted in some constructions sectors. Their increasing adoption has been supported by many research studies that guided the definition standards and guidelines for testing and design. Nevertheless some aspects of their behaviour have not yet been deeply studied and understood; for instance the effect of temperature variations on concretes with polymeric fibres has received limited attention in the literature. In this framework, the present paper presents a study on the influence of temperature variation on macro-synthetic fibers for FRCs. In particular, single polypropylene fibers were tested at different temperatures, 20°C, 40°C, 60°C, 80°C, and different rates, under tensile load, analyzing how the increment of temperature affects their strength and elastic modulus
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