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The present paper describes the experimental setup for flow-induced vibration in a fuel pin bundle test section with flowing lead. The test section is a 37-pin mock-up representative of the GEN-IV ALFRED fuel assembly and is manufactured to investigate the turbulence-induced vibrations in the pins. The pins are instrumented with longitudinal strain gauges (SGs), and with three SGs per monitoring point, the displacement signal can be recovered in terms of amplitude and frequencies. To achieve this goal, a complex algorithm is implemented in the data acquisition control system of the test section. The test section will be installed in the Heavy Liquid metal Experimental loop for Nuclear Applications (HELENA) facility at the ENEA Brasimone R.C., in which a mechanical pump for lead circulation is present. The test matrix is proposed with the mass flow rate varying from 10 to 50 kg/s and a constant temperature of 450°C for all the tests. Briefly, the experimental procedure is presented to carry out the experimental campaign. [ABSTRACT FROM AUTHOR]

Sin resumen.

Gypsum has been widely used in traditional and monumental architecture in many countries of the Mediterranean area; however, due to its low water resistance and low mechanical strength, it can be subject to physical, chemical and biological degradation. To improve the preservation of gypsum-based plaster artifacts, a new hybrid inorganic-organic hydrophobic treatment is proposed in this work. This treatment is based on nanometric magnesium hydroxide (Mg(OH)₂) and organically modified silica (OrMoSil), a class of materials with intermediate performances between ceramic materials and polymers. The behaviour of the product was verified both as a protective on gypsum surface, as well as a consolidant added to the mixture of gypsum-based plasters. The treatment does not alter the aesthetic appearance of the surface, as verified through colorimetric analysis. As demonstrated by capillary water absorption and static contact angle measurements, the new hydrophobic protective coating proved to be very effective. Moreover, the new treatment is effective as a consolidant, leading to an improvement of the mechanical properties and to a reduction of the depth of carbonation. The new hydrophobic nanocomposite product is therefore a promising material for the protection and consolidation of gypsum monuments and artifacts of cultural interest.

This work deals with the development of innovative cement-free plastering mortars with enhanced thermal properties. To this end, one-part alkali-activated slag-based materials were manufactured, by adding aluminum powder as expanding agent to reduce the density and expanded glass to improve thermal insulation. Different recipes were developed by varying the water content and the alkali-activator. The results show that the admixture containing sodium silicate meets the requirements for a lightweight plastering mortar in terms of mechanical strength (class CSII), despite exhibiting slightly elevated thermal conductivity with respect to that required for a type T2 (0.28 vs. 0.20 W/mK). The admixture with potassium silicate shows instead noteworthy values of both density and thermal conductivity, although its mechanical performance is very limited, due to its higher water content. Nevertheless, this last formulation could potentially serve as a viable starting point for the development of a sustainable cement-free construction material for the insulation of the building envelope. Further studies in this direction are currently underway.

This work focuses on the mechanical characterization of the inorganic matrix used for Fiber-Reinforced Cementitious Matrix (FRCM) composites, nowadays widely used to retrofit existing reinforced concrete and masonry structures. While several works in technical literature investigate the experimental behavior of the whole FRCM composite, few information are available on the mechanical characterization of the mortar, which contains polymers and synthetic fibers in its admixture. However, the knowledge of its behavior in tension, especially after crack formation, is an important feature for the calibration of constitutive models to be adopted in the study of structural elements strengthened with FRCM. To this aim, an experimental program was performed on mortar specimens characterized by different shapes and dimensions, tested under direct tension or three-point-bending. From the performed tests, it was possible to characterize inorganic matrix behavior both in the uncracked stage, through the determination of the elastic parameters (elastic modulus and Poisson's coefficient), and in the cracked stage. The use of digital image correlation (DIC) technique also allowed the study of the evolution of crack propagation in the specimens. Lastly, a correlation factor between axial and flexural tensile strength is proposed, for both design and numerical modelling purposes. [ABSTRACT FROM AUTHOR]