1,753 research outputs found
Optimization of flowable concrete for structural design: Progress report of fib task group 8.8
No full textWith the tendency to apply concrete with a higher workability and the use of new concrete components more options are available to design concrete. New concrete types like self-compacting concrete (SCC), ultra-high performance fibre reinforced concrete (UHPFRC) and high performance fibre reinforced cementitious composite (HPFRCC) also require adopted mix designs and in case, a new engineering approach. Flowable concrete not only is an innovative material, but its application can lead to innovative structures, combinations of building materials and alternative and efficient production methods. fib Task Group 8.8 aims at facilitating the use of innovative flowable materials for the design of concrete structures and considers three aspects of flowable concrete for structural design: material properties, production effects and structural boundary conditions. The main objectives of this group of experts are to combine research findings with practical experience and to write a state of-the-art report and a recommendation on the structural design with flowable concrete. Areas of structural design where flowable concrete differs from traditional vibrated concrete have to be identified. This paper reports about the progress of fib TG 8.8 and discusses important aspects related to flowable concrete.Structural EngineeringCivil Engineering and Geoscience
fib Recommendations “Structural Design with floable concrete
No full textFlowable concrete (either compacted with some vibration or self-compacting) is becoming a more and more widely applied building material. Due to its flowable nature, reinforcing bars can become an obstacle, mixture components may float or segregate and the casting technique determines the orientation of fibres, if any. An increasing range of components is available to optimize their mixture composition to achieve both rheological characteristics and hardened state properties which are more suitable to the selected application. As a result, concrete optimization becomes a crucial task to the development of successful applications.
In April 2009, fib-Task Group (TG) 8.8 'Structural Design with Flowable Concrete' started to facilitate the use of innovative flowable materials for the design of concrete structures. Taking into account research findings and practical experience, the main objectives of fib TG 8.8 are to write a state-of-the-art report and recommendations on the structural design with flowable concrete. fib TG 8.8 considers three aspects of flowable concrete: material properties, casting (production and manufacturing) techniques and boundary conditions of a structure.
This paper presents the scope of fib TG 8.8 concerning the potential and the characteristics of flowable concrete, discusses related design standards and recent developments. fib TG 8.8 aims at promoting the application of flowable concrete and its future implementation in guidelines and codes
Evaluation of the first automated thyroglobulin assay
Get PDFThe aim of this study was to investigate technical and analytical performance of the first automated thyroglobulin (Tg) assay (DPC-Immulite(R); Diagnostic Products Corporation, Los Angeles, USA). In imprecision studies using several human serum pools ranging from 21 to 58 replicates, a coefficient of variation of 9.0 % was obtained at a mean Tg concentration of 0.84 ng/ml and of 6.1 % at a Tg concentration of 62.1 ng/ml. In a method comparison with a non-automated assay (BRAHMS LUMItest Tg(R), BRAHMS, Berlin, Germany) using 383 sera of 303 patients with thyroid carcinoma, regression analysis according to Passing and Bablock yielded in the following equation: Immulite Tg=1.6 x BRAHMS Tg - 0.1 ng/ml (Pearson's r=0.979). Sera obtained from 59 patients with thyroid carcinoma enabled comparative follow-up studies; in all cases qualitative agreement was found with regard to increase or decrease of serum Tg; in eight cases, however, Tg was detected with the Immulite assay but not with the BRAHMS assay. Further follow-up proved the presence of thyroid tissue in these patients. From these and further methodological data (dilution linearity, interference studies, carry-over study, high-dose hook properties, and short report time) it is concluded that the DPC-Immulite Tg assay meets the requirements of routine diagnostic use
Structural design with flowable concrete: a fib-recommendation for tailor-made concrete
No full textFlowable concrete (either compacted with some vibration or selfcompacting)
is becoming a widely applied building material. Due to its flowable
nature, reinforcing bars can become an obstacle, mixture components may float or
segregate and the casting technique determines the orientation of fibres, if any. An
increasing range of components is available to optimize concrete concerning
rheological and hardened state properties and for the application under
consideration. Flowable concrete offers an extended range of engineering
properties and the potential for product innovation.
fib Task Group (TG) 8.8 'Structural Design with Flowable Concrete' started
in 2009 to facilitate the use of innovative flowable materials for the design of
concrete structures. Taking into account research findings and practical
experience, the main objectives of fib TG 8.8 are to write a state-of-the-art report
and recommendations on the structural design with flowable concrete. fib TG 8.8
considers three aspects of flowable concrete: material properties, production
effects and structural boundary conditions.
This paper discusses the scope of fib TG 8.8 concerning the characteristics
and the potential of flowable concrete and presents related design standards. fib
TG 8.8 aims at promoting the application of flowable concrete, improving and
adapting the concrete design and production technology and its implementation in
guidelines and codes
Structural design with flowable concrete
Get PDFFlowability is a characteristic of concrete with a high workability in the fresh state. In order to achieve flowability the mix design can be considerably different compared to vibrated concrete. Not only the production technique has to be adapted to the higher flowability, but the flow can also cause local differences in material behaviour. With deviating mix design, constitutive laws and provisions related to the structural behaviour established for VC might no longer be applicable. This paper discusses the progress of fib TG 4.3, a Task Group that aims at facilitating the use of innovative flowable materials for the design of concrete structures by providing a state-of-the-art report and recommendations for the structural design with flowable concrete
fib-Task Group “Structural Design with flowable concrete
No full textFlowable concrete is evolving from a special type to a widely applied building material. Design guidelines have to consider recent developments on the field of innovative, performance-based materials and production technology. The new fib-Task Group 8.8 (Structural design with flowable concrete) started in 2009 to facilitate the use of innovative flowable materials for the design of concrete structures. Taking into account research findings and practical experience, the main objective of fib TG 8.8 is to write recommendations on the structural design with flowable concrete. Main aspects of the structural design process are to achieve strength, durability and, in case, aesthetical appearance. In order to pursue this goal when using flowable concrete, a 'holistic approach' is needed which has to combine the following three aspects: material properties, casting (production and manufacturing) techniques and the shape of the structure. Due to the flowable nature of such types of concrete, rebars can become an obstacle, components may float or segregate and the casting technique determines the fibre orientation.
This paper describes the scope of fib-Task Group 8.8, discusses existing design rules for high performance concretes and indicates the potential of flowable concrete. An international commission works on establishing a basis for the future implementation of flowable concrete in design guideline
Design of concrete for high flowability. Progress report of fib Task Group 8.8
No full textFlowable concretes can differ significantly from traditional vibrated concrete. Concrete types like self-compacting concrete (SCC), ultra-high performance concrete (UHPC) and high performance fibre reinforced cementitious composites (HPFRCCs) require novel mix design approaches. This has consequences for the production and the performance in the hardened state. Mix designs for flowable concretes can incorporate a wide variety of innovative admixtures or components: e.g. superplasticisers increase the flowability and allow for significant reduction of the water content, shrinkage compensating admixtures or superabsorbent polymers support sound and damage free curing processes, viscosity modifying admixtures enhance the robustness, and new fibre types allow for sophisticated and tailored structural performance.
The new Model Code has limitations regarding the application of flowable concrete, e.g. thresholds for the minimum aggregate size and the maximum strength. Provisions are added to include fibres for structural design. fib Task Group 8.8 aims at facilitating the use of innovative flowable materials for designing concrete structures and considers three aspects of flowable concrete: material properties, production effects and structural boundary conditions and performance. This paper reports about the progress of fib TG 8.8 related to the mix design of flowable concrete and discusses the present state-of-the art concerning admixtures and robustness
Design with highly flowable fiber reinforced concrete: overview of the activity of fib TG 8.8
No full textSelf-Compacting Fiber Reinforced Concrete (SC-FRC) combines the
benefits of highly flowable concrete in the fresh state with the enhanced
performance in the hardened state in terms of crack control and fracture toughness
provided by the wirelike fiber reinforcement. Thanks to the suitably adapted
rheology of the concrete matrix, it is possible to achieve a uniform dispersion of
fibers, which is of the foremost importance for a reliable performance of structural
elements. Balanced viscosity of concrete may also be helpful to drive the fibers
along the concrete flow direction. An ad-hoc designed casting process may hence
lead to an orientation of the fibers “tailored” to the intended application, which is
along the anticipated directions of the principal tensile stressed within the structural
element when in service. This converges towards a “holistic” approach to the
design of structure made with highly flowable/self consolidating FRC, which
encompasses the influence of fresh state performance and casting process on fiber
dispersion and orientation an the related outcomes in terms of hardened state
properties. The fib task Group 8.8 “Structural design with highly flowable
concrete”, sub-group fiber concrete, appointed in April 2009, aims at drafting
recommendations to facilitate and spread the use of these innovative materials,
merging together research findings and practical experience
Bulk viscosity in F(T, TG) gravity
Get PDFThe present paper is devoted to exploring the effect of bulk viscosity in the context of F(T, TG) gravity. We consider a time-dependent viscosity model with a particular expression of Hubble parameter. We evaluate viscous effective equation of state parameter for three well-known F(T, TG) models. The behavior of the accelerated expanding universe is explored graphically through the viscous equation of state parameter. This parameter indicates the phantom-dominated era as well as crosses the phantom divide line for all three models. We conclude that the universe shows a transition from quintessence to phantom region in the presence of bulk viscosity.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
The LIM and SH3 domain protein family: structural proteins or signal transducers or both?
No full textLIM and SH3 Protein 1 (LASP-1) was initially identified from a cDNA library of metastatic axillary lymph nodes (MLN) more than a decade ago. It was found to be overexpressed in human breast and ovarian cancer and became the first member of a newly defined LIM-protein subfamily of the nebulin group characterized by the combined presence of LIM and SH3 domains. LASP2, a novel LASP1-related gene was first identified and characterized in silico. Subsequently it proved to be a splice variant of the Nebulin gene and therefore was also termed LIM/nebulette. LASP-1 and -2 are highly conserved in their LIM, nebulin-like and SH3 domains but differ significantly at their linker regions. Both proteins are ubiquitously expressed and involved in cytoskeletal architecture, especially in the organization of focal adhesions. Here we present the first systematic review to summarize all relevant data concerning their domain organization, expression profiles, regulating factors and function. We compile evidence that both, LASP-1 and LASP-2, are important during early embryo- and fetogenesis and are highly expressed in the central nervous system of the adult. However, only LASP-1 seems to participate significantly in neuronal differentiation and plays an important functional role in migration and proliferation of certain cancer cells while the role of LASP-2 is more structural. The increased expression of LASP-1 in breast tumours correlates with high rates of nodal-metastasis and refers to a possible relevance as a prognostic marker
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