bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerische Simulation von Temperaturgradienten und thermisch induzierten Eigenspannungen in Natursteinplatten infolge von Sonneneinstrahlung / Simulation of Temperature Gradients and Stresses in Natural Stone Plates under Solar Radiation
Authors: Sadouki H. , Wittmann F. H.
Published: November 2014

The interaction between micro-organisms and natural stone surfaces has been studied in great detail in the past. The destructive mechanisms of micro-organisms can be roughly subdivided into (a) chemical attack and (b) physical attack. Microorganisms may physically destroy the structure of stones by creating an inter-granular swelling pressure. Recently, it has been shown experimentally that black spots formed by yeast-like fungi lead to a local temperature increase by selective absorption of solar radiation. The maximum temperature observed for clean marble surfaces remained below the maximum temperature observed on inoculated surfaces. As a consequence, thermal dilatation of inoculated marble was shown to be more important. Destruction of the heated stone occurs predominantly if there exists a thermal gradient. In this paper, temperature distribution in clean and stained marble plates have been simulated numerically. Thermal eigenstresses have been determined. It is shown that tensile stresses of up to 5 N/mm2 can be expected. This may cause damage in weak zones of the surface. A sudden driving rain leads to much higher stresses. Cyclic thermal loading may eventually destroy the surface by fatigue.
Bestimmung der Feuerwiderstandsdauer von Fachwerkwänden / Determination of the Fire Resistance Period of Half-timbered Walls
Authors: Leimer H.-P.
Published: November 2014

As there are no certificated qualification for the fire resistance period of halftimbered walls different walls with and without claddings were tested. The tests were carried out in a small fire chamber and are based on DIN 4102. On the basis of the tests the dependence of the building elements and materials according tofire were revealed. It was obvious that careful sealings mainly in the area of joints could reduce the passage of fire and thereby the failure of the whole construction. Good sealings are clay and other insulating mortars that are used for infillings. Good sealing materials are further plaster and/or insulating plaster layers just as panel kind materials like gypsum and fire prevention boards. The present results are not able to replace a test according to DIN 4102 Τ 2/3 but they can be helpful for a judgement of an individual expert's opinion.
Nachträgliches Abdichten erdberührter Bauteile / Sealing of Structural Elements in Contact with Soil at a Later Stage
Authors: Kabrede H.-A.
Published: November 2014

In order to seal structural elements which are in contact with soil at a later stage, external and internal sealing has been the usual practice for years. It is the aim of this contritution to point out the possibility of sealing by means of area injection in a structural element and veil injection in the soil. Both methods can be applied under water pressure. In particular, the requirement frequently formulated by representatives of service for the protection of monuments to seal a structure at a later stage without modifying the surface of historical structural elements is taken into consideration. Measures are discussed which may be applied if the serviceability of a new structure is jeopardized by water infiltration. Restoration methods, restoration planning and the necessary apparatus are described. In addition, the injection materials to be used are indicated depending on the water pressure.
Qualitätssicherung einer Parkdeckinstandsetzung mit Kunstharzbeschichtungen / Quality Control of a Car Park Repair Carried out by Means of Resin Coatings
Authors: Giger B.
Published: November 2014

The following article will describe the procedure of quality control of a car park repair with synthetic resin coating. Basic prerequisites for the realisation of the quality control are exact knowledge of the condition of the building, the assessment of possible repair variants, the necessary know-how in product application as well as the definition of the limits to be observed. The example shows that frequently the quality of the work carried out is improved in the process of construction up to a satisfactory level. Due to constant quality control, faults were discovered in time. Quality control has proved to be successful provided that all parties involved are behind this concept and are prepared to carry through the quality requirements defined.
Baustoffanalyse mit Infrarotspektroskopie / Analysis of building materials by infrared spectroscopy
Authors: Salzer R. , Lunkwitz R. , Braun T. , Mühle M.
Published: November 2014

Modern methods of instrumental analysis provide very convenient ways to characterize building materials. At present, wet chemical procedures are still in use not only for sample preparation but also for the real investigation. Raster electron microsopy and x-ray diffraction are the preferred instrumental methods of analysis in many places. In this review the high potential of optical molecular spectroscopy for characterization of building materials will be demonstrated by typical examples. Extensive series of wet chemical analysis may be substituted even by a single IR spectroscopic measurement combined with modern procedures of chemometric data evaluation.
Typische Schäden in verputzten Sockelbereichen / Typical damages at renderings in base zones
Authors: Goretzki L. , Reisek D.
Published: November 2014

Damage at renderings in base zones caused by splash water are often observed. During this procedure, different situations have been investigated. Several types of renderings and paint systems as well as the exposition of the buildings are taken into consideration. Suggestions for higher durability of renderings in the base zone are made.
Quantitative Betrachtung der Sulfatdeposition bei Sichtmauerwerksbauten / Fair-faced brick masonry - Estimation of the deposition of sulphates
Authors: Franke L. , Schumann I.
Published: November 2014

Deterioration of the surface layer of brick masonry' facades is often due to accumulation of gypsum. While the source of the sulphates is the wet and dry deposition of SO,, the main supplier of the Calcium are the joints. The enrichment of salts may lead to damages within in the brick due to crystallisation pressures and the mechanical properties of the joints will suffer from the reduction of binder. Furthermore. the accumulation of gypsum will cause severe changes in the drying behaviour of the building material, which will enhance the microbiological colo nisation and induce later damages due to frost action in special cases.
Sanierungsvorschlag für den Turm der Oberkirche in Bad Frankenhausen / A proposal for the restoration of an inclining church tower at Bad Frankenhausen
Authors: Findeisen C. , Michalik I. , Schleußner H.-P. , Slowik V.
Published: November 2014

The tower of the Oberkirche at Bad Frankenhausen is inclining as a result of ground movements. Based on earlier documents and on the results of additional experimental investigations, a new safety evaluation has been undertaken. Furthermore, the authors tried to numerically simulate the geodynamic processes taking place in the ground by using geological models. As a result, a technical proposal for the preservation of the structure is presented.
Zum Reaktionsverhalten präkambrischer Grauwacken im alkalischen Milieu von Betonen / The reactions of precambrian greywackes in an alkaline pore solution of concretes
Authors: Hünger K.-J. , Wollgarn H. , Rathnow R. , Frey R.
Published: November 2014

Two precambrian greywackes GW1A and GW1C with different structures were investigated to describe their reaction behaviour in concrete. A portlandcement CEM I, 32,5 with a high alkali content (Na2O-eq. = 1,4 %) was used. The soluble constituents of the greywackes in the alkaline pore solution of the concrete were determined by using a special method of chemical concrete analysis. The concrete samples were storaged in a special fog chamber at 40 °C and 100 % rel. humidity until to 9 month. The following conclusions can be given:

1 The concrete samples which were made with greywacke GWIA show a damage value of about 4 to 5 by means of rifts observed. Analogeous to the damage it can be found that the concentration of the soluble constituents which were release from greywacke begins at zero and increases continual}· until the end of the investigation. A specific discussion of several soluble oxides shows enormous differences between the reactivity of certain constituents investigated.

2 The concrete samples which were manufactured with greywacke GWIC show a damage value of about 1...2 only. But the quantity of the soluble constituents which come from the greywacke is higher. Characteristically here is a shoot up of the soluble constituents after beginning of the cement hydration process. After this the content of the soluble constituents decreases again. This behaviour in chemical reactivity of greywacke investigated can be declared by different structures. The mainly differences between both the GWIA and the GWIC were the size of the greywacke constituents. The chemical reactivity which was determined immediately after the alkali attack of the pore solution of the hardened cement and the macroscopical reactivity observed by means of rifts after 9 month are not the same.
Thermotrope Materialien für den Einsatz in „intelligenten Fenstern" / Thermotropic materials for application in "intelligent windows"
Authors: Seeboth A. , Holzbauer H.-R.
Published: November 2014

Thermotropic materials as integrated part of „intelligent windows" based on polymer gel networks are developed. Systems change the transparency in dependence on temperature. These windows are able to protect buildings against superheating by sunshine. The aim of this work is the formation of a thermotropic material which operates like a heat filter. The effect is based on reproducible reversible phase transitions in the material. A decisive aspect is the adjustment of these transitions between the optical clear or opaque state of the windows, controled by the solar energy, to the perception of the human eye.
Einfluss der Betonuntergrundrauhigkeit auf das Haftvermögen zementgebundener Beschichtungen / Influence of the surface roughness of a concrete substrate on the adhesion of a cement-based coating
Authors: Trausch J.-L. , Wittmann F.H.
Published: November 2014

Concrete overlays are often used for the repair of damaged concrete surfaces. The material propreties of the concrete overlay are different from those of the substrate. Restraint of shrinkage and thermal strains result in tensile stresses. At the free boundaries of the system the tensile stresses reach a maximum value. If these values reach the adherence strength, strain softening and then delamination occur starting from the free boundaries. The adherence behaviour of such a repair layer depends on the surface roughness and could be characterized by the wedge splitting test by use of non-linear fracture mechanics. The surface roughness of the substrate could be determinated and correlated to the adherence behaviour of concrete repair layers.
Die Bohrwiderstandsmeßmethode / A Method to determine the resistance with respect to drilling
Authors: Kugele C.
Published: November 2014

The German Centre for Craftsmanship and Preservation of Historic Monuments performs intensive help oriented towards practical applications of a testing apparatus for non-destructive assessment of the condition of historical wooden structures. Possibilities and limits of a resistance drilling measuring apparatus are clearly demonstrated using as an example the Peace Church of the Holy Trinity at Swidnica, Poland, which is a monumental timber-framed building serving for a congregation of 7500. By means of the above mentioned apparatus, the task of assessing the condition of the completely faced and painted interior supporting structure was successfully solved. Damage inside the timber as well as structural changes, types of joints, species of timber, and the load transferring capability of the joints were determined. The restoration of the church dealing with these aspects is nearly completed. One can state that there were no "bad surprises " and the estimated expenditures could be maintained. This is an excellent result, especially in such a sensitive and cost-intensive area like the restoration ofhistoric monuments.
Selection of Consolidants for Use on the Tower of Belem / Auswahl eines Steinfestigers für den Turm von Belem
Authors: Rodrigues J. Delgado , Pinto A.P. Ferreiro , Charola A.E. , Aires-Barros L. , Henriques F.M.A.
Published: November 2014

During the exterior conservation project of the Tower of Belem, Lisbon, it was noticed that although most of the Lioz limestone used in its construction was in good condition, some specific areas presented severe powdering and flaking deterioration patterns. These are mainly due to the effect of natural weathering, including anthropogenic air-pollution, on poorer quality Lioz limestone. Since the deterioration affects mainly the immediate surface and subsurface of the stone blocks, the application of stone consolidants was considered as the most appropriate solution for this problem. This paper describes the difficulties encountered in the evaluation of the tested consolidants-an ethyl silicate ester, an acrylic resin and an epoxy resin-applied in situ. The laboratory and on-site testing used in the final selection are described as well as the actual approach to consolidating the different areas that required this treatment.
Einfluss von Rissen in hydrophobiertem Beton auf den kapillaren Wassertransport / Influence of cracks in water repellent concrete on capillary water movement
Authors: Limit P. , Wittmann F.H.
Published: November 2014

In practice, hydrophobing impregnation has been established as an effective surface protection system against water and de-icing salt attack. Cracks in concrete, whether impregnated by a hydrophobing treatment or not, are unavoidable and can therefore lead to damage. In absorption tests on laboratory samples, the significant influences of cracks on the penetration behaviour of capillary water have been determined and quantified. The experimental results show that the water uptake depends on the craclc width and the penetration depth of the hydrophobing agent. There exists a 'critical' crack width depending on the penetration depth of the hydrophobing agent which can maintain the hydrophobing behaviour. Finally practical conclusions of the present work are drawn.
Abdichtmaterialien gegen drückendes Wasser und Diesel mit verbesserter Umweltverträglichkeit / Sealing Materials against Pressuring Water and Diesel with Optimized Ecotoxicology
Authors: Mang Th. , Haulena F.
Published: November 2014

Sealing materials against pressuring water and leaking diesel have been developed as shaped gaskets, pastes and liquid injection materials based on acrylic polymers. Not only do these have optimized application properties, they are also greatly improved in ecotoxicology and working safety.
Eindringtiefe eines Hydrophobierungsmittels als Funktion der Qualität, des Feuchtigkeitsgehaltes und des Alters des Betons / Penetration depth of a water repellent agent as a function of quality, humidity and age of concrete
Authors: Moetsch H.A. , Meier St. , Gerdes A. , Wittmann F.H.
Published: November 2014

Service life and lifetime of a concrete structure are not only depending on mechanical but also on chemical loads. Therefore precautions are often taken into account already in the planning- or construction phase. Certain protective measures such as water repellent treatment need preliminary tests on the finished concrete surface, in order to be applied in an optimal way . The present paper describes the preliminary tests performed on three tunnels of the second section of the Swiss National Highway N5 (Grenchen - Zuchwil) in the area of Solothurn. For the construction of the three tunnels different qualities of concrete and different types of form work were used. Furthermore the selected sections of the tunnels differ also from age and environmental conditions. A new two-chamber measuring cell developped at the Institute for Building Materials of ΕΤΗ-Zurich was applied to determine the capillary suction capacity of selected tunnel sections. Values measured on concrete elements in practice with this new cell are much more reliable than those measured with the traditional Karsten-cell.
Schutzbehandlung von Beton mit Silan- und Siloxanpräparaten / Protective Treatment of Concrete with Silane or Siloxane
Authors: Nyman B.
Published: November 2014

By means of laboratory experiments it is shown that the penetration depth of a treatment of concrete with Silane depends strongly on the duration of suction and on the moisture content of the concrete. The necessary duration of suction can be estimated for any required penetration depth.
Bestimmung der Haftzugfestigkeit dichter Beschichtungen / Determination of bond strength of impermeable polymer coatings
Authors: Frey R.M. , Wittmann F.H.
Published: November 2014

In many cases there is a risk for the formation of blisters if impermeable polymer coatings are applied on porous substrates. On covers of courses in sport stadiums formation of blisters has been observed recently. In this contribution a method is described which can be used to investigate the causes of blister formation in a given system. Blisters are artificially created by the application of a gas pressure in the interface between coating and substrate. In this way the growth of blisters can be varied under controlled conditions. The theoretical background of this method is outlined. In this way it is possible to estimate the necessary pressure under the cover to create blisters of the observed size.
Neue kostengünstige rostfreie Stähle für den Einsatz bei korrosionsgefährdeten Stahlbetontragwerken / New and inexpensive stainless steels for use in reinforced concrete structures in agressive environment
Authors: Rechsteiner A. , Speidel M. O.
Published: November 2014

Stainless steel is essentially applied in structural elements in which chemical and mechanical loads are combined and which hardly allow periodic checks. Fixations are typical examples. In case of failure dramatic consequences have to be expected. This is also valid for steel reinforcement in concrete. It is exposed to combined chemical and mechanical load, it can hardly be controled and damage leads at least to enormous costs of repair. Due to the fact that up to now the expenditures for construction are rarely considered together with the expenditures for maintenance, the use of stainless steel is still exceptional. If it is possible, however, to produce cheap steel with a corrosion resistance comparable to steel 1.4401 or even better, wide spread use of stainless steel as concrete reinforcement should be possible. New types of austenitic and duplex steel as being developed in the Laboratory for metal research of Swiss Federal Institute of Technolog (ΕΤΗ) in Zurich without Ni seem to be promising materials. In this case it is tried to replace expensive components by cheap ones such as nitrogen.
Prediction of Durability of Concrete in Monuments using Fracture Mechanics / Vorhersage der Dauerhaftigkeit von Beton in Baudenkmalen durch Anwendung der Bruchmechanik
Authors: Leonovich S.N.
Published: November 2014

The extension of cracks and pores are considered to be a theoretical basis for the prediction of durability of concrete of monuments. For this purpose a two-level structural model has been introduced: (I) matrix of hardened cement paste with fine and coarse aggregates, (2) voids and cracks created by external actions. The main parameter of this approach is the critical stress intensity factor: [xxx] The stress intensity factor of the material in the vicinity of the crack tip governs the crack growth. If all micro- and macro-defects are taken into consideration on the different levels of the hierarchic structural system, it is possible to formulate the global response. Each pore or crack creates a characteristic stress field around its­ elf in the material. If these pores are classified into periodic volume elements, the individual stress fields can be superimposed. This results in the complex state of stress under an imposed deformation.
On-site and Laboratory Investigation of Materials and Structure of a Belltower in Monza / Untersuchungen an den Werkstoffen und am Tragwerk im Labor und am Objekt am Beispiel eines Glockenturms in Monza
Authors: Binda L. , Tiraboschi C. , Folli R. Tongini
Published: November 2014

After the collapse of some heavy buildings and towers in Italy and elsewhere, the hypothesis of possible continuous damage to these structures due to the dead weight and cyclic loads (wind, temperature variations, etc.) has been formulated by the authors. The long term behaviour of historic masonry has also been detected by laboratory creep and cyclic tests. The results indicate that a laboratory and on site investigation together with analytical modelling are important particularly for tall bell-towers. The application of these procedures on the Bell-Tower of the Cathedral of Monza is here reported and discussed
Spannungsrißkorrosion von Spannstahl - Vorstellung einer neuen Untersuchungsmethode / Stress corrosion of prestressing steel reinforcement - Presentation of a new test method
Authors: König G. , Krumbach R. , Heyn A.
Published: November 2014

The origin of the susceptiblility of prestressing steel reinforcement with respect to stress corrosion and the observed failure mechanisms can be described 'in detail. So far, however, no precise method exists to determine the sensitivity of prestressing reinforcement or to distinguish different types of steel with respect to their susceptiblility for stress corrosion. This fact leads not only to prejudices in practice but also to additional safety measures (f.e. robust reinforcement), which implies economical consequences. The aim of a cooperation project between the Institute of Concrete Structures and Building Materials Technology at Leipzig University and the Institute for Materials Technology and Testing at Otto-von-Guericke- University Magdeburrg is to develop a general acceptable test method which provides us quickly with meaningful results. It turned out that the observation of electrochemical noise is a promising method to study stress corrosion of prestressing steel reinforcement. This method can be applied both in laboratory testing and under site conditions and can therefore also serve as a basis for corrosion monitoring.
Electrolytes in narrow pores / Electrolyten in engen Poren
Authors: Churaev N.V. , Setzer Μ.J. , Wowra О. , Reick Μ.
Published: November 2014

Mean electrolyte concentration Cm in narrow charged pores decreases as a result of repulsion of co-ions from charged walls. The theory of electrical double layers (EDL) was used for calculation of this effect in dependence on surface potential values Φ1 and concentration C0 of bulk electrolyte solutions. The calculations were limited to the case of 1-1 electrolytes and low values of surface potentials Φ1 when simple analytical solutions may be used. Mean concentration of chloride ions and neutral solution in narrow negatively charged slit pores of different thickness h was calculated in dependence on Φ1 and Debye radius values. It was shown that the effect is more pronounced in narrow pores at relatively high absolute values of surface potentials and at low concentration of a bulk solution. In narrow hydrophilic pores, a decrease in mean electrolyte concentration results from the effect of dielectric exclusion caused by decreasing values of dielectric constant of water ef. The calculations were performed using Born equation that relates the self-energy of ions W with the 8f values and ion radii. Comparing the results obtained with measured values of rejection coefficients of electrolyte solutions in reverse osmosis membranes, the dependence of £f values on pore sizes was calculated. Repulsive forces arising in narrow pores as a result of overlapping of EDL are calculated in dependence on slit thickness, bulk solution concentration and surface potentials in the framework of the theory of electrostatic component of disjoining pressure. In the case of hydrophilic silica systems molecular attraction forces and repulsive structural forces were also taken into account. The arising structural forces are caused by overlapping of boundary layers of water with modified structure
Anwendung einer geo-elektrischen Untersuchungsmethode für Mauerwerk im Rahmen eines Instandsetzungsvorhabens / Geo-Electrical Survey of Masonry for Restoration Projects
Authors: Venderickx K. , Van Gemert D.
Published: November 2014

Geo-electrical relative difference mapping is presented as a non-destructive evaluation technique for ancient masonry. The method allows to visualise the internal structure and condition of the masonry. The decision on the necessity and on the type and degree of consolidation or strengthening of the masonry wall can be based on the information, obtained from the mapping. The paper deals with the arrangement of the original measurements to make them suitable for engineering evaluation. Firstly a numerical model is presented to filter out the influence of geometrical boundary conditions: they distort the measurements, but are of no interest for the evaluation. Secondly the maps are calibrated, to eliminate the influence of measuring configuration, and moisture content. The calibration methods are presented, and applied on the resistivity measurements, executed at the restoration project of the building "Duke's Mills" (13th Century) at Aarschot (B).
Bestimmung der Wasser- und Salzgehaltsverteilung durch Kombination von NMR- und γ-Durchstrahlungsmessungen / Determination of water and salt content distributions by means of combined NMR- and γ-transmission measurement
Authors: Holm A. , Künzel H.M.
Published: November 2014

When a masonry loaded with salt is exposed to natural weather conditions there are occurring two interdependent mechanisms of transport: moisture- and salt transport. For the purpose of investigating these coupled processes, the Fraunhofer- Institute of Building Physics developed a measurement technique which allows a non-destructive determination of both water content distribution and salt content distribution in capillary porous building materials. This system includes two different nuclear physical measurement procedures: Nuclear Magnetic Resonance (NMR) and gamma-ray attenuation. The NMR unit produces a signal that depends just on the number of protons in the specimen. Because of this, the water content of the specimen is linked to the signal of the NMR-measurement. During a gamma-ray attenuation measurement salt and water content distribution are gauged simultaneously. The larger the density of the measured specimen is, the stronger is the attenuation of the gamma-rays when they pervade the matter. By combining the results of these two measurement methods it is possible to determine the salt and water content distribution simultaneously in a non-destructive way. From this profiles it is possible to draw conclusions in respect of the occurring transport processes and the correlative parameters such as for example capillary transport coefficients and water absorption coefficients of salt loaded building material. These results yield the preconditions for first concrete basic approaches to describe the coupled moisture and salt transport and furthermore the influence of the salt on the moisture transport. Lately numerous absorption tests on Sander Sandstone were carried out. The specimens sucked saline solutions of different salts and concentrations. After defined time steps the profiles of water and salt content were measured. Furthermore tests during the drying period were preformed on specimens loaded with defined saline solutions.
Kathodischer Korrosionsschutz für Stahlbetontragwerke unter Verwendung eines neuen leitfähigen Anstrichsystems / Cathodic Corrosion Protection of Steel Reinforced Concrete Structures with a New Conductive Composite Paint System
Authors: Schwarz W.
Published: November 2014

Corrosion of steel in concrete is one of the critical problems in civil engineering with regard to the durability of reinforced concrete structures. Cathodic protection (CP) of the steel rebars in concrete structures evolved during the past 25 years as a reliable method to extend the lifetime of reinforced concrete structures. During the CP operation, proportional to the applied protection current, acids are generated at the anode/concrete interface. This effect limits durability and performance of various CP-systems. This contribution describes a newly developed conductive composite paint for use as anode material, characterized by high durability at high current densities and easy applicability, and its practical application for the corrosion protection of a parking deck in Oslo.
Die Verwendung von Systemen zur dauernden Überwachung der Korrosion in neuen und bestehenden Stahlbetontragwerken / The Use of Permanent Corrosion Monitoring in New and Existing Reinforced Concrete Structures
Authors: Broomfield J.P. , Davies K. , Hladky K.
Published: November 2014

Corrosion monitoring systems consisting of linear polarisation, concrete resistivity and other probes have been installed in new structures to monitor durability and in existing structures to evaluate rehabilitation strategies such as corrosion inhibitor application and patch repairs. The types of sensors used, data collection techniques, results and interpretation are discussed.
Effect of silane coupling agent on the mechanical properties of nitrile butadiene rubber (NBR)/organophilic montmorillonite (OMMT) nanocomposites
Authors: Zhang Ru Liang , Zhao Li Fen , Huang Yu Dong , Liu Li
Published: November 2014

The effect of coupling agents on the mechanical properties of nitrile butadiene rubber (NBR)/organophilic montmorillonite (OMMT) clay nanocomposites was studied using three different types of silane coupling agents, which were γ-(aminopropyl)triethoxysilane, γ-(mercaptopropyl) triethoxy silane, and bis-[(γ-triethoxy silane)proply] tetrasulfur. The NBR/OMMT nanocomposites were prepared via the melt compounding with OMMT clay. The effect of silane coupling agents on the dispersion of OMMT in the polymer matrix was studied by X-ray diffraction. Dynamic mechanical analysis was employed to investigate the mechanical properties change induced by the silane coupling agents. The results suggest improved mechanical properties for the nanocomposites with coupling agents of γ-(mercaptopropyl) triethoxy silane and bis-[(γ-triethoxy silane)proply] tetrasulfur, whereas reduced mechanical properties were observed for nanocomposites with γ-(aminopropyl)triethoxysilane.
Modeling cement hydration by connecting a nucleation and growth mechanism with a diffusion mechanism. Part I: C3S hydration in dilute suspensions
Authors: Pang Xueyu , Meyer Christian
Published: November 2014

A particle-based C3S hydration model, which mathematically connects a nucleation and growth controlled mechanism with a diffusion controlled mechanism, is developed in this study. The model is first formulated and fitted with C3S hydration in stirred dilute suspensions in Part I where interactions between different particles can be ignored, and further developed and fitted with Portland cement paste hydration in Part II to account for inter-particle interactions. Excellent agreement was observed between experimental and modeled results. Three critical rate-controlling parameters, including a parallel growth rate constant, a perpendicular growth rate constant and a diffusion constant, were identified from the proposed model. The dependencies of these parameters on particle size and initial quantity of nuclei are investigated in Part I while their dependencies on cement composition, water-cement ratio, and curing condition are studied in Part II.
Electron Transfer Reaction of Ion Pairs: 1.  Surfactant Cobalt(III) Complexes by Fe(CN)6
4− in Microheterogeneous Media
Authors: Nagaraj Karuppiah , Senthil Murugan Krishnan , Thangamuniyandi Pilavadi
Published: November 2014

The kinetic study of reduction of single chain surfactant octahedral
cobalt(III) complexes,
cis-[Co(en)2(4AMP)(DA)](ClO4)3 and
cis-[Co(trien)(4CNP)(DA)](ClO4)3 (where
en = ethylenediamine; trien = triethylenetetramine;
4AMP = 4-aminopyridine; 4CNP = 4-cyanopyridine;
DA = dodecylamine) with [Fe(CN)6]4–
has been
carried out by spectrophotometric method under pseudo first order
conditions using an excess of a reductant in different media namely,
micelles, β-cyclodextrim (β-CD), liposome vesicles (DPPC)
and ionic liquids ((BMIM)Br) at different temperatures in order
to have deep insight into the molecular behavior during the electron
transfer reaction. The analysis of kinetic results strongly suggests
that the reduction reaction between the surfactant complex and
[Fe(CN)6]4–
occurs via a second order outer sphere
electron transfer mechanism. The remarkable increase in the rate of
electron transfer from the oxidant to reductant is observed in ionic
liquid medium as compared to the rest of all other media studied in
the present investigation. This can be ascribed due to the fact that
the formation of aggregated and constrained geometry of the surfactant
cobalt(III) complexes (oxidants) in ionic liquid medium renders the
rate of one electron transfer from the oxidants to the reductant,
[Fe(CN)6]4–
to be higher. Furthermore, the rate constant
value increases with increase in the concentration of micelles,
however in the presence of β-cyclodextrin medium the rate of
electron transfer substantially decreases due to the inclusion of long
aliphatic chain of the surfactant cobalt(III) complexes into
β-cyclodextrin. In liposome media, second order rate constant
for this electron transfer reaction from both the oxidants was found
to decrease with increase in the concentration of the liposome below
the phase transfer temperature of DPPC. However, above the phase
transition temperature the reaction was found to increase with
increase in the concentration of the DPPC. The main driving force for
this phenomenon is considered to be the intervesicular hydrophobic
interaction between the surfactant complexes and vesicular
surface. The activation parameters
(ΔS‡ and
ΔH‡)
of this outer sphere
electron transfer reaction have been calculated by varying
temperatures and the analysis of the data corroborates the kinetics of
the reaction.
Formation of Oxygenated and Hydrocarbon Intermediates in
Premixed Combustion of 2-Methylfuran
Authors: Moshammer Kai , Lucassen Arnas , Togbé Casimir , Kohse-Höinghaus Katharina , Hansen Nils
Published: November 2014

This paper focuses on the combustion chemistry of 2-methylfuran
(2-MF), a potential biofuel, and it is built on the previous work of
Tran et al. [Combust. Flame 161 (2014) 766]. In
their work, they had combined detailed flame chemistry modeling with
flame speciation data based on flame-sampling molecular beam mass
spectrometry (MBMS) with electron ionization and gas chromatography
with MS detection. In this work, we significantly extend those
previous studies by in-situ isomer-resolving species
identification and quantification. Specifically, we have determined
the detailed chemical structure of a premixed laminar 2-MF flame using
flame-sampling high-resolution MBMS with synchrotron-generated
vacuum-ultraviolet radiation. Mole fraction profiles of 60
intermediate, reactant, and product species were measured in order to
assess the pollutant potential of this possible next-generation
biofuel. Special emphasis is paid towards the fuel's ability to form
aromatic and oxygenated intermediates during incomplete combustion
processes, with the latter species representing a variety of different
classes including alcohols, ethers, enols, ketones, aldehydes, acids,
and ketenes. Whenever possible the experimental data are compared to
the results of model calculations using the 2-MF combustion chemistry
model of Tran et al., but it should be noted that many newly
detected species are not included in the calculations. The
experimental data presented in this work provides guidance towards to
development of a next-generation 2-MF combustion chemistry model.
Simplified Descriptions of Cool-Flame Chemistry
Authors: Williams Forman A.
Published: November 2014

Correct detailed chemical-kinetic descriptions of the consequences of
the additions of oxygen molecules to alkyl radicals involve large
numbers of elementary steps. The resulting complexity of the system of
equations needed to describe combustion processes often taxes
computational capabilities. Simplified descriptions of the chemical
kinetics that retain essential elements of the results therefore can
be useful for a number of purposes, even though they fail to include
many of the chemical processes. Such simplified descriptions for
combustion processes are presented here for certain normal
alkanes. Their potential utility and prospects for future developments
are discussed.
Bone metastases and skeletal-related events from neuroendocrine tumors
Authors: Van Loon Katherine , Zhang Li , Keiser Jennifer , Carrasco Cendy , Glass Katherine , Ramirez Maria-Teresa , Bobiak Sarah , Nakakura Eric K , Venook Alan P , Shah Manisha H , Bergsland Emily K
Published: November 2014

Neuroendocrine tumors (NETs) metastasize to bone; however, a multi-institution evaluation of the natural history and complications of bone metastases across multiple NET subtypes has not, to our knowledge, previously been conducted. At two tertiary academic centers, we identified patients with bone metastases from databases of patients with a diagnosis of NET between 2004 and 2008. Detection of bone metastases, occurrence of skeletal-related events (SREs), and interventions were analyzed using summary statistics and categorical methods. Time-to-event data were assessed using Kaplan–Meier estimates and log-rank tests. Between 2004 and 2008, 82 out of 691 NET patients (12%) were reported to have bone metastases. Of the 82 patients with bone metastases, 55% were men and their median age was 49. Bone metastases occurred in 25% of pheochromocytomas and paragangliomas, 20% of high-grade neuroendocrine carcinomas, 9% of carcinoid tumors, and 8% of pancreatic NETs. At time of detection of bone metastases, 60% reported symptoms, including pain; 10% developed cord compression, 9% suffered a pathological fracture, and 4% developed hypercalcemia. Occurrence of SREs did not differ significantly with regard to tumor histology. Of patients with bone metastases, 67 (82%) received at least one form of bone-directed treatment, 50% received radiation, 45% received a bisphosphonate, 18% underwent surgery, 11% received 131I-MIBG, 5% received denosumab, and 46% were treated with more than one treatment modality. Bone metastases occur in a substantial number of patients diagnosed with NETs. Patients are often symptomatic and many develop SREs. Given the recent therapeutic advances and increasing life expectancy of patients with NETs, development of guidelines for surveillance and clinical care of bone metastases from NETs is needed.
Abnormal plasma sodium concentrations in patients treated with desmopressin for cranial diabetes insipidus: results of a long-term retrospective study
Authors: Behan L A , Sherlock M , Moyles P , Renshaw O , Thompson C J T , Orr C , Holte K , Salehmohamed M R , Glynn N , Tormey W , Thompson C J
Published: November 2014

Context and objective

Patients with cranial diabetes insipidus (CDI) are at risk of developing both hypernatraemia and hyponatraemia, due to the condition itself or secondary to treatment with vasopressin-analogues or during administration of i.v. fluids. We aimed to assess the frequency and impact of dysnatraemias in the inpatient (INPT) and outpatient (OPT) setting in desmopressin-treated CDI, comparing those with normal thirst with those with abnormal thirst.

Design

The study included 192 patients with cranial diabetes, who were identified from the Beaumont Pituitary Database, a tertiary referral centre. Retrospective case note audit was performed and the clinical and biochemical information of 147 patients with CDI were available for analysis.

Results

A total of 4142 plasma sodium measurements for 137 patients with normal thirst, and 385 plasma sodium measurements for ten patients with abnormal thirst were analysed. In those with normal thirst, the most common OPT abnormality was mild hyponatraemia (pNa+131–134 mmol/l) in 27%, while 14.6% had more significant hyponatraemia (pNa+≤130 mmol/l). Of those patients with normal thirst, 5.8% were admitted due to complications directly related to hyponatraemia. Compared with patients with normal thirst, those with abnormal thirst were more likely to develop significant OPT hypernatraemia (20% vs 1.4%,P=0.02) and significant INPT hyponatraemia (50% vs 11.1%,P0.02).

Conclusion

OPT management of CDI is complicated by a significant incidence of hyponatraemia. In contrast, OPT hypernatraemia is almost exclusively a complication seen in adipsic CDI, who also had more frequent INPT hyponatraemia. CDI associated with thirst disorder requires increased physician attention and patient awareness of potential complications.
Climate threats to the earth-built heritage of Scotland
Authors: Parkin Simon J. , Paul Adderley W. , Kennedy Craig J. , Aktas Yasemin Didem , D'Ayala Dina , Erkal Aykut
Published: November 2014

The most significant concentration of surviving vernacular mudwall structures in Scotland is found in and around the town of Errol in the Carse of Gowrie. Mudwall, or cob, is particularly susceptible to climate-related impacts such as water ingress and freeze–thaw cycles. A lack of recognition can exacerbate the effects of these factors significantly. Using two sites as representative case studies, this paper considers the issues typically encountered. The procedures used in monitoring the performance of each building within a regional climate context are outlined. Using climate models and current weather data, the local climatic context within which these structures exist is considered. Climate-related impacts can then be considered for future scenarios. Temperature and humidity data were collected concurrently from targeted areas within the walls of both structures for over a year from April 2012, a period that exhibited a range of extreme weather events in the Carse of Gowrie. The system of datalogging at each structure is discussed and results considered against external weather conditions using decomposed time series statistical analysis. Recommendations are offered considering how an integrated approach to the analysis of historic mudwall structures can be achieved.
Recent research and development of ground column technologies
Authors: Han Jie
Published: November 2014

In recent years, ground columns, such as vibro-concrete columns and geosynthetic-reinforced stone columns, have been increasingly used to support superstructures and embankments when they are constructed on soft foundations. Several new column technologies have emerged, including different shapes of concrete columns and composite columns. The column technologies have also been combined with other technologies to create more effective and/or economic solutions. However, the composite columns and the combined technologies have presented complicated geotechnical problems in design and construction. This paper summarises different types of column technologies and their functions, installation and applications, addresses design issues, and reviews recent research and development related to the column technologies to improve soft foundations, including failure modes, load transfer mechanisms, bearing capacity, settlement, consolidation and stability. Recent research has indicated that lateral deformation and yielding of columns should be considered in a unit cell model for the analyses of load transfer, deformation and consolidation. Several theoretical solutions have been proposed for the rate of consolidation of column-reinforced soft foundations. Different failure modes should be evaluated for the stability of column-supported embankments. Limit equilibrium methods based on shear failure overestimate the factors of safety of embankments on rigid or semi-rigid columns in soft soil.
Steel fibre reinforcing effects on engineering properties of cement-less concretes with AAS
Authors: Jang Seok-Joon , Ahn Kyung-Lim , Kang Dae-Hyun , Yun Hyun-Do
Published: November 2014

This study experimentally investigated mechanical and impact performances of an alkali-activated slag (AAS) concrete reinforced with hooked-end steel fibres. The compressive, flexural and impact behaviour of AAS concrete with different volume fractions (0·0%, 0·5%, 1·0%, 1·5% and 2·0%) of steel fibre were evaluated. To examine the impact resistance of steel fibre reinforced AAS concrete, a total of 20 panel specimens (200 mm wide, 200 mm long and with a constant thickness of 50 mm) were fabricated and subjected to spherical projectile impact at velocities ranging from 150 m/s to 300 m/s measured by an electro-optical device. Projectiles of diameter 20 mm and mass 38 g were accelerated using a laboratory gas gun, and the impact resistance of the AAS concrete panels was assessed from their resistance to projectile impact in terms of average crater diameter, penetration depth and average scabbing diameter after impact testing. The main findings indicate that the addition of hooked-end steel fibres to AAS concrete improves mechanical properties such as compressive and flexural strength and impact performance. These results indicate that this new cement-less concrete may be an optimal alternative to conventional ordinary Portland cement concrete for various applications in the construction industry.
New glass design method for adhesive point-fixing applications
Authors: Dispersyn Jonas , Belis Jan , Sonck Delphine
Published: November 2014

Stress concentrations in glass plates connected with adhesive point-fixings are much lower than when connected with traditional bolted point-fixings. For the investigation of adhesive point-fixings, a complex finite-element model is usually required. Based on the method of superposition of local and global components SLG method, for bolted point-fixings, a design method is developed for adhesive point-fixings to simplify the finite-element analysis. This is done by separating the glass plate into a local and a global component. The local component represents only a part of the glass plate, with one adhesive point-fixing, and is modelled with more complex finite-element volume elements. The global component represents the entirety, and is modelled with less complex shell elements. The total stress distribution is obtained by superposition of the results of the local and global components. This paper describes how this method is developed and validated. The local numerical model is calibrated based on strain measurements obtained from experiments. The results show that the SLG method can be suitable for adhesive point-fixings as well, which enables a simplified and faster design.