Exploring the possibilities of steel-fiber reinforced self-compacting concrete for the flexural strengthening of masonry structural elements

The potentialities of a thin layer of steel fibre reinforced self-compacting concrete (SFRSCC) for the flexural strengthening of handmade brick structural elements are investigated. For this purpose an experimental program was carried out covering the relevant phenomena that can influence the effectiveness of this technique. The SFRSCC has a post-cracking residual tensile strength capable of improving the flexural stiffness, flexural resistance and ductility of prototypes representatives of ancient handmade brick based structures that fail in bending. To appraise the flexural strengthening effectiveness of this technique, straight beams composed of handmade bricks, low strength mortar (LSM) and SFRSCC were tested. The obtained results have shown that this technique can increase significantly the flexural stiffness and resistance, and the ductility performance of 2 this type of structures. The strengthening effectiveness depends on the post-cracking residual strength of the SFRSCC, its layer thickness and on the possibility of replacing part of the LSM by SFRSCC. Based on the experimental results for the characterization of the intervening materials, and adopting a cross section layer model capable of predicting the moment-curvature relationship for the distinct types of cross sections of this structural system, the maximum load registered in the tested prototypes was predicted with good accuracy.The study reported in herein is part of the research program “PrePam– Pre-fabricated thin panels using advanced materials for structural rehabilitation”, PTDC/ECM/114511/2009, supported by FCT. The authors would like to acknowledge the support provided by the Civitest Company, where the major part of the tests was carried out

Flexural strengthening of masonry members using advanced cementitious materials

Two different cement based fiber reinforced composites for the flexural strengthening of masonry beams under monotonic loading are studied. Steel Fiber Reinforced Self- Compacting Concrete (SFRSCC) with tensile strain-softening behavior, and PVA fiber reinforced cement based mortar (SHCC) with tensile Strain-Hardening were the developed composites. Both composites were applied on the tensile surface of masonry beams and the effectiveness of this technique for the flexural strengthening of these quasi-brittle structural elements was assessed by performing four point beam bending tests. Both materials contributed effectively to increase the load carrying capacity and ultimate deflection ductility of the tested masonry beams, but, higher average values were obtained for these two indicators of the strengthening effectiveness when using a layer thickness of SHCC that is 2/3 of the thickness of SFRSCC. Furthermore, much more homogenous results, in terms of forcedeflection relationship, were obtained with masonry beams strengthened with SHCC than with SFRSCC

Shareholder Value vs. Nachhaltigkeit?

Die Bedeutung der Börse als weltweiter Vermittler von Eigenkapital hat in den letzten Jahren zugenommen. Daher hat für die börsennotierten Unternehmen auch die Ausrichtung der unternehmerischen Leistung auf eine Steigerung ihres Geldwertes, des Shareholder Value, an Bedeutung gewonnen. Wer sich heute mit Zielkonflikten und Synergien zwischen Marktwirtschaft und nachhaltiger Entwicklung auseinandersetzen will, tut gut daran, die Rolle der Finanzmärkte zu analysieren und transparent zu machen

Experimental research of high field pinning centers in 2% C doped MgB2 wires at 20K and 25K

High field pinning centers in MgB doped with 2 at. % carbon under a low and a high hot isostatic pressures have been investigated by transport measurements. The field dependence of the transport critical current density was analyzed within the different pinning mechanisms: surface pinning, point pinning, and pinning due to spatial variation in the Ginzburg-Landau parameter (Δκ pinning). Research indicates that a pressure of 1 GPa allows similar pinning centers to Δκ pinning centers to be obtained. This pinning is very important, because it makes it possible to increase the critical current density in high magnetic fields at 20 K and 25 K. Our results indicate that the δT and δl pinning mechanisms, which are due to a spatial variation in the critical temperature (T) and the mean free path, l, respectively, create dislocations. The high density of dislocations with inhomogeneous distribution in the structure of the superconducting material creates the δl pinning mechanism. The low density of dislocations with inhomogeneous distribution creates the δT pinning mechanism. Research indicates that the hot isostatic pressure process makes it possible to obtain a high dislocation density with a homogeneous distribution. This allows us to obtain the δT pinning mechanism in MgB wires. In addition, a high pressure increases the crossover field from the single vortex to the small vortex bundle regime (B) and improves the δT pinning mechanism. Our research has proved that a high pressure significantly increases the crossover field from the small bundle to the thermal regime (B), with only a modest decrease in T of 1.5 K, decreases the thermal fluctuations, increases the irreversibility magnetic field (B) and the upper critical field (B) in the temperature range from 4.2 K to 25 K, and reduces B and B above 25 K

The design, construction, and commissioning of the KATRIN experiment

The KArlsruhe TRItium Neutrino (KATRIN) experiment, which aims to make a direct and model-independent determination of the absolute neutrino mass scale, is a complex experiment with many components. More than 15 years ago, we published a technical design report (TDR) [1] to describe the hardware design and requirements to achieve our sensitivity goal of 0.2 eV at 90% C.L. on the neutrino mass. Since then there has been considerable progress, culminating in the publication of first neutrino mass results with the entire beamline operating [2]. In this paper, we document the current state of all completed beamline components (as of the first neutrino mass measurement campaign), demonstrate our ability to reliably and stably control them over long times, and present details on their respective commissioning campaigns

Laser-acoustic, thermal and mechanical methods for investigations of bond lines

The curing of epoxy adhesives on metal adherends produces interphases near the substrate surface. The detn. of the interphase thickness in small joints will be complicated due to the influence of the adherend. To exclude this effect from the characterization of the interphase, resin-metal-composites were created by spin-coating process of different resin layer thicknesses on the aluminum surface. Before the tests, the coated aluminum was cured. The thickness of the cross-linked epoxy layer ranges between 2 and 150 micro m. These coated sheet metals were characterized by a new laser-acoustic method (LAwave) and by micro-thermal anal. (micro TA). Both methods are non-destructive. LAwave is based on the measurement of laser-induced surface waves. It enables the Young's modulus of thin films to be detd. The micro TA was used for studying the interphase formed composites based on aluminum and epoxy resin. It is a thermo-anal. technique that combines the principles of scanning probe microscopy with thermal anal. This allows samples to be spatially scanned in terms of both topog. and thermal cond. It is possible to perform localized thermal anal. expts. on discrete small regions with high resoln. The results were compared with results of mech. (nanoindentation) investigations. We could detect an interphase of some micrometers (about 25 micro m) between the aluminum surface and the epoxy-bulk phase

Pilot study of psychiatric and social aspects of children and adolescents with fragile X syndrome [Pilotstudie zu psychiatrischen und sozialen Aspekten bei Kindern und Jugendlichen mit Fragilem-X-Syndrom (FRX)]

Objective: The study describes the burden of psychosocial risks of mental illnesses and the ways in which children and adolescents with fragile X syndrome (FRX) can be treated. Method: Data from a sample of 34 patients with FRX younger than 18 years stemming from a prospective multicenter (n = 11) registry study (EXPLAIN) were analyzed with regard to psychosocial burden and treatment. Results: One third of all participants reported having relatives who suffer from FRX. The majority of participants were suffering themselves from one kind or another mental or neurological problems. Younger participants (< 14 years) tended to suffer from atactic disorders, epileptic seizures, and autistic symptoms. These disorders were usually treated by psychotropic drugs supplemented by logopedic therapies and occupational therapies (more than once a month). In our sample, 96.3 % of the younger patients and more than 57.1 % of the older patients were still living with their parents. Conclusions: Patients with FRX often suffer from additional neurological and mental disorders. For that reason, they should be diagnosed and treated early on