An experimental set-up for cyclic loading of concrete

Abstract Innovative cementitious composite materials are drawing considerable interest due to their substantially improved mechanical properties as compared to ordinary cement-based materials. Their enhanced ductility is promising and particularly suited to structural applications under severe dynamic loading conditions. Cyclic response is essential to understand the effects of loading and unloading on the material, as well as to understanding how it behaves in the transition from tension to compression. It is also fundamental to identify its properties in terms of energy dissipation and strain-rate sensitivity. This paper presents the first part of an ongoing research project which aims to develop the constitutive relationship in innovative cementitious composites and its numerical implementation. Results from this research will facilitate the investigation of the ductility and durability of existing buildings. In this paper, an experimental set-up for uniaxial cyclic loading is described. It was developed to study reversed cyclic compression/tension loadings of innovative cementitious composites. To set the cyclic loading process, cylindrical specimens of concrete were tested. All the tests were performed on a Zwick testing machine with 50 kN load cell. The machine was customised with accessories specifically designed to meet test requirements, avoiding instability and bending moments during the alternating phases of uniaxial compression and tension. Strain gauges were used to measure lateral deformations. The customized machine has shown good performance so far. In order to test specimens with a higher number of cycles and a higher loading rate, improvements to the machine are currently under development. These tests will allow greater insight into the ductility of innovative cementitious composite materials

influence of pyrolysis parameters on the efficiency of the biochar as nanoparticles into cement based composites

Abstract In this research, a particular kind of biochar provided by UK Biochar Centre has been added as nanoparticles into cementitious composites. Its principle characteristic lies in the standardization of its process production, that makes it suitable to been used as filler in cement-matrix composites, ensuring the reproducibility of the cement mix (I. Cosentino "The use of Bio-char for sustainable and durable concrete", 2017). The pyrolysis parameters and the content of carbon in the standardized biochar influenced its efficiency to enhance the mechanical properties of the cement composites: the results, in terms of flexural strength and fracture energy, have been worse than those obtained in previous studies (L. Restuccia "Re-think, Re-use: agro-food and C&D waste for high-performance sustainable cementitious composites", 2016), in which particles have been produced with higher temperature. However, also with standardized biochar a general enhancement of mechanical properties has been recorded, a sign that they can be used to create new green building materials

Cyclic uniaxial testing and constitutive modelling of cementitious composite materials

Innovative cementitious composite materials are drawing considerable interest due to their substantially improved mechanical properties, as compared to ordinary cement-based materials: among the others, higher tensile strength, tensile strain hardening, flexural strength, fracture toughness [1] and resistance to fatigue. Their enhanced ductility appears to be promising and particularly suited to structural applications under severe dynamic loading conditions (earthquake, impact, blast) [2]. Accurate constitutive models to simulate the dynamic behaviour of cementitious composites are hence needed, as well as corresponding appropriate testing protocols for their experimental characterisation [3]. In this study, the response of cementitious composites to cyclic uniaxial loadings has been investigated. Cyclic response is essential to understand the effects of unloading and reloading on the material, to examine how it behaves in the transition from tension to compression and to characterise its properties in terms of energy dissipation and strain-rate sensitivity. Different loading schemes have been considered, including reversed cyclic tension/compression loadings, in order to identify the complete stress-strain curve and the transition behaviour, which can occur, for instance, under seismic, fatigue and wind loads. Monotonic quasi-static tension and compression tests have been also performed, to provide a benchmark for the evaluation of the envelope curve of cyclic response. The experimental campaign was carried out on cylindrical specimens, a standard geometry in compression testing of cement-based materials. Several series of homothetic specimens (height to diameter ratio fixed as 2) with different dimensions were tested, to evaluate the influence of scale effects. Variability and reproducibility of the testing results have been taking into account by employing a minimum number of three specimens per loading condition. All the tests were performed, under deformation-controlled regime, on an MTS servo-hydraulic testing machine with 250 kN load cell. The testing machine was customised with accessories designed to meet specific test requirements, avoiding instability and bending moments during the alternating phases of uniaxial compression and tension. Linear variable displacement transducers (LVDT) and strain gauges were used to measure vertical displacements and lateral deformations, respectively. The results obtained experimentally represent a reliable basis for the development of constitutive models suited to numerical simulation. References [1] Restuccia, L., Reggio, A., Ferro, G.A., Kamranirad, R., “Fractal analysis of crack paths into innovative carbon-based cementitious composites”, Theoretical and Applied Fracture Mechanics, 90, 133-141, 2017. [2] Yoo, D. Y., Banthia N. “Mechanical properties of ultra-high-performance fiber-reinforced concrete: A review”, Cement and Concrete Composites, 73, 267-280, 2016. [3] Kesner, K.E., Billington, S.L., Douglas K.S. “Cyclic response of highly ductile fiber-reinforced cement-based composites”, ACI Materials Journal, 100(5), 381-390, 2003

Nano CaCO3 particles in cement mortars towards developing a circular economy in the cement industry

Abstract This paper calls into question the effects of incorporating nano calcium carbonate (CaCO3) particles in cement mortars, as they are interesting additive materials already successfully tested as cement nanofiller. These nanoparticles could potentially be prepared through the carbonation route using CO2 from combustion gases from the cement industry. This could enable a circular-economy approach for carbon capture and its re-use within the cement industry, in a sustainable and synergistic manner. In this study, part of the cement content was substituted with commercial nano CaCO3 particles to investigate their effects on the flexural and compressive strength of the resulting cement mortars, after curing for 7 and 28 days. Decreasing the cement content could lead to a reduction in the carbon footprint of cement, which is responsible for approximately 8% of global carbon dioxide emissions. Preliminary results using synthesized CaCO3 particles as nanofillers showed that, after 7 days of curing, mechanical properties of cement mortars improved. This indicates that hydration reaction was accelerated since CaCO3 acts as seeding for this reaction. By contrast, after 28 days of curing, no major improvement was observed. A higher content of calcium carbonate nanoparticles may have reduced the filler effect of these particles due to aggregation phenomena. In the present work, the effects of commercial nano CaCO3 particles on cement hydration were investigated. Mechanical tests showed promising results both after 7 and 28 days of curing. This could lead to the reduction of the carbon footprint of cement manufacturing and produce increasingly better performing building materials. Thus, the development of a circular economy in the cement industry could be achieved

Report of two cases of influenza virus A/H1N1v and B co-infection during the 2010/2011 epidemics in the Italian Veneto Region

From October 2010 to April 2011, in the Italian Veneto Region, 1403 hospitalized patients were tested for influenza virus infection by specific real time RT-PCR. Overall, 327 samples were positive for either influenza A (75%) or B (25%) viruses. Among these positive patients two resulted co-infected by A/H1N1v and B viruses. Even though co-infection with both influenza A and B viruses appears to be a rare event, it occurs naturally and may play a role in epidemiology and pathogenicity. In the present study the two co-infected patients were a transplant recipient immunocompromised adult and a child displaying a severe respiratory illness. The co-infection was confirmed by inoculation of the nasopharyngeal swabs in MDCK.2 cells, followed by immunofluorescence and real time RT-PCR assays. Moreover, in the case of the adult patient, the immune system response against both viruses was assayed by hemoagglutination inhibition test against reference influenza virus strains. Both patients fully recovered from infection, without significant differences with mono-infected patients

Firm mass in thyroid of an elderly patient: not always cancer

Summary In elderly patients presenting with a solid thyroid mass, the differential diagnosis between benign and malignant lesion is not always straightforward. We present the case of an 85-year-old woman with fever and an enlarged, firm and painful thyroid mass. Blood exams documented a mild thyrotoxicosis with a moderate inflammatory status. Thyroid scintiscan showed an absent uptake of 131I. Ultrasound and CT scan documented a 3 cm hypoechoic nodule with infiltration of the sternocleidomastoid muscle, very suspicious for neoplastic nature. Fine-needle aspiration and tru-cut biopsy were performed. During biopsy, the lesion was partially drained and a brownish fluid was extracted. The culture resulted positive for Klebsiella pneumoniae whereas the pathological analysis of the specimen was not conclusive due to the presence of an intense inflammatory response. A targeted oral antibiotic therapy was then initiated, obtaining only a partial response thus, in order to achieve a definite diagnosis, a minimally invasive hemithyroidectomy was performed. The pathological analysis documented acute suppurative thyroiditis and the clinical conditions of the patient significantly improved after surgical removal of thyroid abscess. In elderly patients with a solid thyroid mass, although neoplastic origin is quite frequent, acute suppurative thyroiditis should be considered as a differential diagnosis. Learning points: A solid and rapidly growing thyroid mass in elderly patients can hide a multifaceted variety of diseases, both benign and malign. A multidisciplinary team (endocrinologist, surgeon, radiologist and pathologist) could be necessary in order to perform a correct differential diagnosis and therapeutic approach. Surgery can be decisive not only to clarify a clinically uncertain diagnosis, but also to rapidly improve the clinical conditions of the patient

The instrument control unit of the ESA-PLATO 2.0 mission

PLATO 2.0 has been selected by ESA as the third medium-class Mission (M3) of the Cosmic Vision Program. Its Payload is conceived for the discovery of new transiting exoplanets on the disk of their parent stars and for the study of planetary system formation and evolution as well as to answer fundamental questions concerning the existence of other planetary systems like our own, including the presence of potentially habitable new worlds. The PLATO Payload design is based on the adoption of four sets of short focal length telescopes having a large field of view in order to exploit a large sky coverage and to reach, at the same time, the needed photometry accuracy and signalto- noise ratio (S/N) within a few tens of seconds of exposure time. The large amount of data produced by the telescope is collected and processed by means of the Payload's Data Processing System (DPS) composed by many processing electronics units. This paper gives an overview of the PLATO 2.0 DPS, mainly focusing on the architecture and processing capabilities of its Instrument Control Unit (ICU), the electronic subsystem acting as the main interface between the Payload (P/L) and the Spacecraft (S/C)

Global Architecture of Planetary Systems (GAPS), a project for the whole Italian Community

The GAPS project is running since 2012 with the goal to optimize the science return of the HARPS-N instrument mounted at Telescopio Nazionale Galileo. A large number of astronomers is working together to allow the Italian community to gain an international position adequate to the HARPS-N capabilities in the exoplanetary researches. Relevant scientific results are being obtained on both the main guidelines of the collaboration, i.e., the discovery surveys and the characterization studies. The planetary system discovered around the southern component of the binary XO-2 and its characterization together with that of the system orbiting the northern component are a good example of the completeness of the topics matched by the GAPS project. The dynamics of some planetary systems are investigated by studying the Rossiter-McLaughlin effect, while host stars are characterized by means of asteroseismology and star-planet interaction