bluuebunny/crossref_metadata_2025 huggingface dataset:
Water Transport Properties and Depth of Chloride Penetration in Ultra High Performance Concrete
Authors: Dobiáš Daniel , Pernicová Radka , Mandlík Tomáš
Published: September 2016

Properties of water transport and depth of chloride penetration into the Ultra High Performance Concrete (hereafter as UHPC) with mild steel fibres are presented in this paper. The main aim of this experimental part of work is to obtain sufficiently accurate input data for the evaluation of long-term durability of architectural concrete which are connected with water transport and its accompanying effects such as biological degradation or chloride transport. The article also presents the one dimensional chloride diffusion into UHPC which can be potentially dangerous particularly for durability of reinforced concrete structures. For the simulation of aggressive environments the concrete samples were exposed to chloride solution for one year. Measured data were examined in relation to the depth of penetration of chloride ions into the UHPC structure. Comparative measurements with normal strength concrete (hereafter as NSC) are done as well. An about five-time lower value of moisture absorption of UHPC compared to the NSC was observed and further the curve of chloride penetration into the structure is significantly steeper for UHPC samples.
Impact Properties of Hemp Fibre Reinforced Cementitious Composites
Authors: Zhou Xiang Ming , Madanipour Reza , Ghaffar Seyed
Published: September 2016

The construction industry has seen an incredibly fast increase in utilizing natural fibres for making low-cost building materials to achieve sustainable construction. One of such applications is natural fibre-reinforced cementitious materials for either structural or non-structural purpose. Impact properties are engineering properties received increasing attentions from engineering community for structural materials. This research therefore studies impact resistance of hemp fibre reinforced cementitious composites at early ages. Hemp fibre with various lengths, 10 mm and 20 mm, are utilized to reinforce cementitious materials. Hemp fibre reinforced cementitious composite slabs were tested under repeating dropping mass till failure at the age of 7, 14 and 28 days. Cracking behaviour, impact resistance, absorbed impact energy and survived impact blows upon failure are qualitatively/quantitatively analysed. It has been found that 20 mm-long hemp fibre reinforcement leads to higher impact resistance, more absorbed impact energy and survived more impact blows upon failure. Cementitious composite slabs reinforced by 20 mm-long hemp fibres exhibit higher impact crack resistance ratio than those reinforced by 10 mm-long fibres. Longer fibres are more effective in inhibiting the growth of micro-cracks and blunting the propagation of micro-cracks before they join up to form macro cracks leading to ultimate failure.
Ultra High Performance Fiber Reinforced Concrete Behavior under Static and High Velocity Impact
Authors: Pontiroli Christophe , Erzar Benjamin , Buzaud Eric
Published: September 2016

To evaluate the vulnerability of ultra-high performance fiber reinforced concrete (UHPFRC) infrastructure to rigid projectile penetration, CEA-Gramat has led since few years an experimental and numerical research program in collaboration with French universities.
During the penetration process, concrete is subjected to extreme conditions of pressure and strain-rate. Plasticity mechanisms as well as dynamic tensile and/or shear damages are activated during the tunneling phase and the cratering of the concrete target. Each mechanism has been investigated independently at the laboratory scale and the role of steel fibers has been specially analyzed to understand their influence on the macroscopic behavior.
In parallel, some improvements have been introduced into the concrete model developed by Pontiroli, Rouquand and Mazars (PRM model), especially to take into account the fibers contribution in the tensile fracture process. The capabilities of the PRM model have been illustrated by performing numerical simulations of material characterization experiments. Next step will be to assess the concrete model to simulate projectile penetration into UHPFRC concrete structures.
Effect of Fiber Type and Fiber Hybrids on Strain-Hardening and Multiple Cracking Properties of the Ultra-High Performance Cementitious Composites under Uniaxial Loads
Authors: Guo Li Ping , Lei Dong Yi
Published: September 2016

Five series of strain hardening ultra-high performance cementitious composites (SHUHPCC) incorporated with different types of fibers and hybrid fibers were produced. Three types of fibers (steel fiber, polyvinyl alcohol fiber and polyethylene fiber) were used as mono or hybrid reinforcement in SHUHPCC with the same volume fraction of 2%. The primary strengths, strain hardening and multiple cracking behaviors of hybrid fiber reinforced SHUHPCC under the uniaxial tensile are investigated. Test results show that the SHUHPCC containing PE fibers exhibited higher strain hardening capacity and lower first cracking strength than composites reinforced with mono PVA fiber or mono steel fiber. The composites containing PVA fibers or steel fibers have higher tensile strength and first cracking strength than the composite reinforced by mono PE fiber. Hybridization reinforcement with different fibers is able to make up defects of mono fiber reinforcement for SHUHPCC. The change laws of tensile strength and uniaxial compression strength of SHUHPCC with mono PE fiber and mono PVA fiber are opposite to each other.
Effect of w/cm and Composition on Correlations of Concrete Electrical Resistivity and Chloride Migration Coefficients
Authors: Presuel-Moreno Francisco J.
Published: September 2016

The performance with regard to chloride penetration of specimens made with three base compositions (supplementary cementitious materials: 20% fly ash, 20% fly ash + 8% silica fume, and 50% slag replacement by weight of cement), and water-to-cementitious ratios of 0.35, 0.41, or 0.47 were investigated here. In this investigation, laboratory experiments were carried out to study the correlation between electrical resistivity and non-steady state chloride ion migration coefficients (Dnssm) of concrete. NT Build 492 was used to determine chloride migration coefficients. Rapid migration tests and resistivity measurements were performed several times over two years, and the non-steady state migration coefficient (Dnssm) vs. resistivity values were correlated. Experimental results show that a good correlation was found between electrical resistivity and Dnssm. Based on the relationships developed from this investigation, it appears that the correlations are age and composition dependent.
Concrete Reinforced with Recycled Steel Fibers from End of Life Tires: Mix-Design and Application
Authors: Centonze Giuseppe , Leone Marianovella , Micelli Francesco , Colonna Daniele , Aiello Maria Antonietta
Published: September 2016

The manufacturing technology of reinforced concrete with the use of steel fibers to improve its mechanical properties is well-known and commonly used in civil engineering. Generally, steel fibers as discontinuous reinforcement of the concrete matrix are used to limit the cracking growth following the load application. Thus, the obtained concrete is characterized by an improvement of the typically brittle behavior of the ordinary matrix, mainly referring to toughness and post-cracking behavior.
In this paper the results of a recent experimental campaign carried out at the University of Salento will be discussed. It was designed to study the optimization of concrete mixtures reinforced with recycled steel fibers from end of life tires (ELTs) to be used for the realization of precast panels. This experimental campaign is part of a wider research project aimed to validate the idea that the constituent elements of the ELTs, especially rubber and steel, can be effectively reused in concrete mixtures. Taking into account the high annual amount of ELTs generated around the world and their negative impact on the global environmental sustainability, the recovery of their constituent materials and their reuse as raw materials in different technologies, is certainly an excellent way for a sustainable development.
Effect of Carbonation and Sulphate on Chloride Ingress in Cement Pastes and Concretes with Supplementary Cementitious Materials
Authors: Saillio Mickael , Baroghel-Bouny Véronique , Pradelle Sylvain
Published: September 2016

The main cause of premature deterioration of reinforced concrete structures is the corrosion of steel bars, induced by chloride ions (for example in marine environment) and/or by carbonation (atmospheric CO2). At the same time, environmental-induced degradations of concrete can also affect the structure, such as sulphate attack. This can lead to the formation of ettringite, inducing expansion inside the materials and finally degradation. Carbonation, chloride and sulphate ingress are usually studied separately in the literature. This is not representative of in-situ conditions since they can occur at the same time and can have an influence on each other.
In this paper, chloride ingress are studied for concretes and cement pastes partially carbonated or/and in presence of sulphate in chloride contact solution. The mixtures contain OPC alone or with supplementary cementitious materials (SCM). SCMs are here pozzolanic materials (Fly Ash or Metakaolin) or alkali-activated materials such as ground granulated blast furnace slag (GGBS). The materials, partially carbonated (2 months in chamber at 1.5 % of CO2) or not, are put in contact with chloride solutions in presence of sulphate. This study focuses on the apparent chloride diffusion coefficients, as well as chloride binding isotherms which are obtained by the profile method. In addition, some aspects of the microstructure and of the pore structure are investigated, by using Mercury Intrusion Porosimetry and 27Al NMR, in order to better understand the results obtained relatively to the apparent chloride diffusion coefficients and to the chloride binding.
Chloride ingress increases when sulphates are present in the contact solution for all cement materials tested (partially carbonated or not). In addition, chloride ingress is faster when the material is partially carbonated before contact with chloride solution. It appears that both carbonation or presence of sulphate decrease chloride binding, thus explaining the results. The results show an evolution of the properties as a function of the cement replacement ratio by SCMs.
Synthesis of SiO2-PCE Core-Shell Nanoparticles and its Modification Effects on Cement Hydration
Authors: Gu Yue , Ran Qian Ping , Shu Xin , Yu Cheng , Chang Hong Lei , Lv Kai
Published: September 2016

NanoSiO2 was widely used to modify the property of cementitious materials, however, for nanoparticles used in cement-based materials, key problem is the effective dispersion. The surface modification technology can be introduced to promote dispersion of nanoparticles in aqueous system, especially in cement pore solution, which possess high concentration of ions. In this study, at first, NanoSiO2-polycarboxylate superplasticizer (SiO2-PCE) core-shell nanoparticle was synthesized from silanized polycarboxylate superplasticizer and colloidal nanoSiO2 by the “grafting to” method, then SiO2-PCE was testified by UV-Vis, FTIR, and TGA. Additionally, stability of SiO2-PCE and its effect on cement hydration were investigated. Results shows: SiO2-PCE possess higher stability in saturated calcium hydroxide solution compared to nanoSiO2, and heat development of cement hydration can be regulated by shell structure of SiO2-PCE. The research implied a new approach for nanoSiO2 to optimize cement-based composites.
Risk of Delayed Ettringite Formation in Concrete Heated at a Mature Stage: Experimental Quantitative Evidence
Authors: Kchakech Badreddine , Martin Renaud Pierre , Omikrine-Metalssi Othman , Toutlemonde François
Published: September 2016

The conditions of development of Delayed Ettringite Formation (DEF) in concrete when submitted to excessive heating during hydration and setting have deserved recent research efforts and tend to be better understood. However, quantitative evidence of DEF risk for concrete submitted to similar heating when mature is still scarce. The experimental program described in this paper confirms the risk of DEF-induced expansion for concrete normally cured, then heated after 90 days of age, when further kept in saturated environment, both for a DEF-prone mix and for a concrete made with a low C3A, low SO3 and low-alkali content-cement.
Durability of Concrete under Combined Exposure Conditions of Chlorides and Sulfates
Authors: In Kwang Jin , Jiang Y.R. , Jung Sang Hwa , Lee Myung Kue , Yoo Sung Won , Oh Byung Hwan
Published: September 2016

Concrete structures are generally subjected to serious deterioration under harsh environment, even though the concrete materials exhibit inherently higher durability than any other construction materials. The service life of concrete structures is directly affected by the durability performance under various conditions. In this regard, many studies have been conducted on the deterioration of concrete structures under various environmental conditions. However, previous studies were confined mostly to the deterioration of concrete structures under single deteriorating factor such as chloride ingress only or sulfate attack only, although real environment is actually a combination of such factors. The purpose of the present study is, therefore, to explore the effects of combined deterioration due to chlorides and sulfates in concrete structures. To this end, comprehensive experimental program has been set up to observe the chloride penetration behavior under combined deterioration conditions of chlorides and sulfates. The test results indicate that the chloride penetration is more pronounced for the case of combined attacks of chloride and sulfates than the case of single chloride attack. The surface chloride content is found to increase with time and this phenomenon is also more pronounced under the combined exposure of chlorides and sulfates. The present study may allow more realistic assessment of durability for such concrete structures which are subjected to combined attacks of chlorides and sulfates.
Effect of Rapid Hardening Cement and Setting Accelerator on the Freeze-Thaw Durability of Fly Ash Concrete
Authors: Badr Atef , Ioannou Socrates , Al Maroof Haidar
Published: September 2016

This paper presents the results of the second phase of an experimental research, which was carried out to investigate the freeze-thaw durability of fly ash (FA) concrete subjected to slow freeze-thaw cycles. The results of the first phase showed that FA had a significant detrimental effect on the freeze-thaw durability concrete. The lower resistance to freezing condition was attributed to the low early strength of FA concrete, at early ages, compared to Portland cement concrete. Therefore, rapid hardening Portland cement (RHPC) and setting accelerator (SA) were introduced, in the second phase, in a bid to modify the early age properties of FA concrete and, hence, enhance its freeze-thaw durability. The weight loss and residual strength of the specimens were assessed after specific number of freeze-thaw cycles. The results showed that the use of rapid hardening Portland cement (RHPC) and/or setting accelerator (SA) enabled earlier demoulding to take place and enhanced the early age strength of FA concrete. However, this did not necessarily improve the freeze-thaw durability of FA concrete. The effect RHPC and SA on the deterioration and residual strength of concrete containing fly ash was indifferent. Therefore, it is suggested that further research is needed to confirm the effect of RHPC and SA on the freeze-thaw durability of fly ash concrete.
High Absorptive Normal Weight Aggregates Used as Internal Curing Agents to Reduce Hot Weather Concreting and Curing Detrimental Effects
Authors: Savva A. Pericles , Nicolaides G. Demetris , Petrou F. Michael
Published: September 2016

The objective of this research was to quantify the effect of the mixing temperature, as well as curing conditions, on concrete mechanical and durability properties. Sixteen mixtures were cast and specimens were tested at various ages. The w/c ratio of the mixtures was kept constant, whereas the type of aggregates, casting and curing temperature varied. A concrete batch was designed using low absorptive Normal Weight Aggregates (NWA), whereas a second concrete batch included High Absorptive Normal Weight Aggregates (HANWA), at a saturated surface dried (SSD) condition. The HANWA were intended to deliver internal curing water (IC) to the mixtures in order to improve their performance. The mixtures constituent materials were conditioned at 22, 30, 35 and 40 degrees Celsius prior mixing. Two different types of curing regimes have been applied, aiming to evaluate the effect on specimens exposed to both hot environmental conditions and also day to night temperature fluctuations, as opposed on identical, water cured specimens. It was observed that the HANWA mixtures had improved mechanical and durability properties, a fact that was attributed to IC.
Influence of Sustained Load on Durability and Service Life of Reinforced Concrete Structures
Authors: Wang Peng Gang , Wittmann Folker H. , Lu Wen Pan , Zhao Tie Jun
Published: September 2016

The influence of an applied high compressive load on strength of concrete has been studied both theoretically and experimentally in great detail in the past. It was observed that load bearing capacity of concrete decreases under the influence of sustained compressive stress. In this contribution the influence of high sustained compressive stress on capillary absorption and on chloride penetration will be described. It was found that under the influence of moderate sustained compressive load the amount of capillary absorbed water decreases. If the sustained compressive load overcomes 50 % of the material’s strength, the rate of capillary absorption increases. This fact can be explained by reduction of the pore space under moderate compressive stress and formation and time-dependent growth of micro-cracks in the composite structure of concrete. Dissolved chloride is filtered out of the aqueous salt solution and remains accumulated in a surface near layer. In this way a high concentration difference of chloride is built up in a short time. This gradient leads to long lasting diffusion of chloride deeper into the pore space. As the diffusion coefficient of dissolved ions in the pore liquid increases with increasing applied compressive load, service life of structural elements under high compressive load will be reduced significantly when exposed to aggressive environment. This fact has to be taken into consideration if service life of reinforced concrete structures is to be predicted in a realistic way.
Drying Depth and Size Effect on Long-Term Behavior of Concrete
Authors: Samouh Hamza , Roziere Emmanuel , Loukili Ahmed
Published: September 2016

This study aims at improving the analysis of drying tests and taking better advantage of the measurements, by studying the influence of the specimen size. One self-consolidating concrete (SCC) was studied during three years. Drying started 24 hours after casting. The tests were carried on three sizes of cylinders: Φ78mm, Φ113mm and Φ163mm, under the same experimental conditions (20±1°C, 50±5% relative humidity). Total and autogenous shrinkages and mass-loss evolutions were monitored according to RILEM recommendations [1].
Assuming that concrete is a homogeneous and non-aging material, a simple model can be written and used to highlight size effects observed in real concrete. By changing the time variable to the ratio of the square root of the time to the notional size of cross-section, the drying curves of different specimen sizes theoretically follow a master curve [2]. However, experimental curves showed upshifts, thus size effect can be highlighted. Phenomena that occur at early age are actually not taken into account by diffusion equation.
This paper introduces a new concept called drying depth as a layer where water loss occurs during the first days without resulting in shrinkage at the specimen level. This depth did not depend of the specimen size. However the relative volume of this layer increases as the size of the specimen decreases, which explains the size effect experimentally observed. The hydric properties of this zone can be assumed to be different from the inner concrete, with a higher porosity and higher permeability. Several phenomena could explain this effect, like the initial particle size distribution with a higher paste proportion near the surface due to the wall effect during casting [3] [4] [5]. Because of early drying hydration stops and this creates a coarser pores in the external layer. Finally, the micro-cracking at the surface induced by the differential shrinkage can also influence the hydric parameters.
Experimental Study on Effects of Fatigue Loading History on Bond Behavior between Steel Bars and Concrete
Authors: Ye Zhiwen , Zhang Wei Ping , Hu You , Gu Xiang Lin
Published: September 2016

This paper presents an experimental investigation on the influence of fatigue loading history on bond behavior between steel bars and concrete. Reinforced concrete specimens were subjected to fatigue loadings with different amplitudes and cycles before undergoing eccentric pull-out tests. Tests revealed that all specimens failed with the splitting of the concrete cover. With increased loading cycles, the concrete in front of transverse ribs usually becomes denser at the beginning. Meanwhile, the initial bond stiffness and the bond strength increased, while the slip corresponding to the peak bond stress decreases. With the further increase of loading cycles, the bond strength begins to decrease after it reaches a critical value. This study determined that for specimens subjected to repeated loading with a larger amplitude, fewer cycles are needed for the bond strength to go up to the critical bond strength.
Compressive Membrane Action Effects on Punching Strength of Flat RC Slabs
Authors: Cantone Raffaele , Belletti Beatrice , Manelli Luca , Muttoni Aurelio
Published: September 2016

The design of reinforced concrete flat slabs in practice can be governed at failure by punching shear close to concentrated loads or columns. Punching shear resistance formulations provided by codes are calibrated on the basis of experimental tests on isolated slabs supported on columns in axisymmetric conditions. Nevertheless, the behavior of flat slabs can be different than isolated specimens due to the potentially beneficial contributions of moment redistributions and compressive membrane actions. Accounting for the significance of these effects, nonlinear finite element analyses are performed with the crack model PARC_CL implemented in Abaqus. This paper aims to investigate a series of punching shear tests on slabs with and without shear reinforcement, different reinforcement ratios and loading conditions accounting for the potential contribution to the enhancement of the punching strength due to compressive membrane action (CMA). The numerical results with a multi – layered shell modeling are then post – processed adopting the failure criterion of the Critical Shear Crack Theory (CSCT). The results pointed out the significant outcomes and differences between standard specimens and actual members showing how the current codes of practice may underestimate the punching capacity.
Impact Resistant Behavior of RC Beam Damaged by Freeze-Thaw Action
Authors: Kurihashi Yusuke , Mizuta Maki , Shimata Akinori , Kishi Norimitsu
Published: September 2016

In this study, in order to investigate the impact resistant behavior of RC beams damaged by freeze-thaw action, falling-weight impact tests for RC beams were conducted taking with/without frost damage as variable. The RC beam used in this study has been damaged by accelerated freeze-thaw cycling. From this experiment, following results were obtained: 1) Elastic modulus and compressive strength of the concrete were decreased due to freeze-thaw action; 2) In the case of damaged beam, many fine cracks were occurred in small input energy; and 3) Deflections of damaged beam was larger than that of non-damaged beam at the same weight-falling height.
Quality Control and Quality Assurance for Concrete Durability
Authors: Gjørv Odd E.
Published: September 2016

The durability of concrete structures in severe environments is not only related to design and materials but also to construction. Thus, much of the observed durability problems can be ascribed due to lack of proper quality control and quality assurance during concrete construction resulting in poorly achieved construction quality. Upon completion of new concrete structures, the achieved construction quality typically shows a high scatter and variability, and during operation of the structures, any weaknesses and deficiencies will soon be revealed whatever durability specifications and materials have been applied. To a certain extent, a probability approach to the durability design can accommodate the high scatter and variability. However, a numerical approach alone is insufficient for ensuring the durability; greater control and improvements in durability also require the specification of performance-based durability requirements which can be verified and controlled during concrete construction in order to achieve quality assurance. For new major concrete infrastructure, documentation of achieved construction quality and compliance to the durability specification should be essential parts of any rational approach to controlling and increasing the durability. In the present paper, a case study is presented which provides comparisons of work performed under performance and prescriptive durability specifications.
Behavior and Design of Post-Installed Rebar Connections under Temperature
Authors: Muciaccia Giovanni , Consiglio Andrea , Rosati Gianpaolo
Published: September 2016

Typical applications for post-installed rebar connections consist in overlapping joints with existing reinforcement or anchoring of the reinforcement at a slab or beam support.
At cold state it may be shown by testing that a post-installed rebar system can develop the same bond resistance with the same safety margin as cast-in-place rebar. Consequently, anchorage length and lap length for post-installed rebars can be calculated as for cast-in-place according to the Eurocode 2 provisions. However, when subjected to temperature, the decay in bond properties for post-installed systems is significantly more dramatic than for cast-in-place rebars.
The paper presents the result of an experimental campaign carried out on a post-installed connection using a vinylester polymer, investigating the effects on the bond strength both of the temperature and of different testing conditions. Finally, design criteria are provided and applied to a typical case study consisting in a post-installed solid slab.
Induced Anisotropic Gas Permeability of Concrete due to Coupled Effect of Drying and Temperature
Authors: Ezzedine El Dandachy Mohamad , Briffaut Matthieu , Dal Pont Stefano , Dufour Frederic
Published: September 2016

An experimental campaign is carried out to study the effect of drying shrinkage and temperature on multi-directional gas permeability of dry concrete. Thermal loadings up to 250°C are applied on concrete samples in cylinder (11×22) and dog-bone forms (total length of 61 cm). Samples are sliced for permeability measurements. Permeabilities in longitudinal and radial directions are addressed. The cylinder samples are first sliced then dried or heated whilst the dog-bone samples are first dried or heated then sliced. The average of initial intrinsic permeability for the slices (5 cm height, 11 cm diameter) obtained from the (11×22) samples is found isotropic and equal to 2.93×10-17 m2. In this case, drying shrinkage is isotropic. Furthermore, it is shown that for the dog-bone samples, drying shrinkage may induce micro-cracks preferentially in a certain direction which induces permeability anisotropy. Finally, the evolution of the normalized intrinsic permeability with respect to initial permeability versus temperature is found isotropic. An exponential fitting of intrinsic permeability versus temperature is found based on experimental measurements.
Development of a Size Effect Law for RC Structures
Authors: Ghannoum Maria , Baroth Julien , Rospars Claude , Millard Alain
Published: September 2016

The work presented is a part of the french ANR (Agence Nationale pour la Recherche) project MACENA (Maitrise du Confinement en Accident), its main objective is to better present the role of concrete heterogeneities in RC structures in the cracking process. This paper aims to develop and use the size effect method (WL2) applicable to RC structures proposed by Sellier and Millard 2014 [1]. The originality of the method lies on introducing a weighting function defined in the direction of the maximum principal stress using a scale length. In this work, an inverse analysis of the method allows to identify this scale length using experimental test series of concrete specimens under tensile load and 3 point bending beams. The approach is then applied to predict the sensitivity of the mechanical behavior of a reinforced concrete tie under tensile load. The method is applied in the elastic phase and allows providing the structural tensile strength corresponding to the first crack which is affected by size effect and plays a key role because cracked and uncracked structures behave in severe environment in a very different way. In FE model, correlated random fields on the tensile strength of the concrete can be generated using the identified scale length to characterize the autocorrelation length.
Examination of the Alkali Silica Reaction on Existing Roads with Use of Cements with Different Alkali Equivalent
Authors: Schneider Martin , Auer Siegfried , Buchegger Andreas
Published: September 2016

In the paper two existing roads in Austria were examined on the focus of alkali silica reaction of concrete. The two roads have different ages. One is more than 50 years old one is round about 20 years old. The exposition was ordinary highway and countryside highway in the mountains. As next the examination takes the stones from the origin and uses different types of cement to examine the background of the alkali silica guidelines for performance tests of alkali silica reaction. The results are very interesting because most of the performance tests are use test cements with ordinary alkali equivalent. Often the used stones not meet the maximum value of loss of mass under the condition of alkali-load. By using alkali reduced cement the results are less than the maximum value of loss of mass under the condition of alkali-load. One of the targets of the examination was the determination of good load conditions for examination of the alkali silica reaction of stones for use in concrete for road structures. The final paper shows all the examinations and the results between the compared cements and the compared test procedures.
Reflection as a strategy to improve management practice: Insights from management education
Authors: Ronnie Linda
Published: September 2016

Orientation: This study examines the role of reflection as a learning strategy for management students and how this process can contribute to developing a cadre of useful and effective managers.Research purpose: Using data from MBA student work, the aim of the study was to explore reflection as a pedagogical strategy to enhance management practice within an emerging market context.Motivation for the study: The development of more rigorous, thoughtful and decision-focussed management is among the challenges facing organisations in South Africa. Within management education, reflection is seen as a potential strategy to address this issue.Research approach, design and method: This qualitative study sampled 513 students’ reflective assignments. Students were given an individual task as a deliberate strategy to reflect on their own learning and provide insight on the benefits and challenges of the process. Coding was conducted along thematic lines.Main findings: The findings showed that students gained self-awareness and insight into their own management and organisational practices. Their application of concepts, tools and techniques was also enhanced, as was their understanding of working with others.Practical implications: Personal growth, transformation and development in terms of current and future management roles were all outcomes of the reflective process. Skills such as probing, analysing and synthesis – all essential to managers – are encouraged through a reflective mindset.Contribution: The findings of this study indicated that a deeper understanding and improved clarity of management and organisational practices ensued as an outcome of the reflective process.
The validation of an educational database for children with profound intellectual disabilities
Authors: Spangenberg Karlien , Corten Lieselotte , Van Rensburg Winnie , Kilian Elizma , McKenzie Judith , Vorster Hein , Jelsma Jennifer
Published: September 2016

Background: The Western Cape Forum for Intellectual Disability took the South African Government to court in 2010 on its failure to implement the right to education for Children with Severe and Profound Intellectual Disability. Subsequently, multidisciplinary teams were appointed by the Western Cape Education Department to deliver services to the Special Care Centres (SCCs). Initially, minimal information was available on this population.Objectives: The purpose is to document the process of developing and validating a database for the collection of routine data.Method: A descriptive analytical study design was used. A sample of convenience was drawn from individuals under the age of 18 years, enrolled in SCCs in the Western Cape. The team who entered and analysed the data reached consensus regarding the utility and feasibility of each item.Results: Data were collected on 134 children. The omission of certain items from the database was identified. Some information was not reliable or readily available. Of the instruments identified to assess function, the classification systems were found to be reliable and useful, as were the performance scales. The WeeFIM, on the other hand, was lengthy and expensive, and was therefore discarded.Discussion and conclusions: A list of items to be included was identified. Apart from an individual profile, it can be useful for service planning and monitoring, if incorporated into the central information system used to monitor the performance of all children. Without such inclusion, this most vulnerable population, despite court ruling, will not have their right to education adequately addressed.
On Residues of Intertwining Operators in Cases with Prehomogeneous Nilradical
Authors: Varma Sandeep
Published: September 2016

Let P = M N be a Levi decomposition of a maximal parabolic subgroup of a connected reductive group G over a p-adic field F. Assume that there exists w0∊ G(F) that normalizes M and conjugates P to an opposite parabolic subgroup. When N has a Zariski dense Int M-orbit, F. Shahidi and X. Yu described a certain distribution D on M(F), such that, for irreducible unitary supercuspidal representations π of M(F) withis irreducible if and only if D( f )≠ 0 for some pseudocoefficient f of π. Since this irreducibility is conjecturally related to π arising via transfer from certain twisted endoscopic groups of M, it is of interest to realize D as endoscopic transfer from a simpler distribution on a twisted endoscopic group H of M. This has been done in many situations where N is abelian. Here we handle the standard examples in cases where N is nonabelian but admit a Zariski dense Int M-orbit.
A Note on Lawton’s Theorem
Authors: Dobrowolski Edward
Published: September 2016

We prove Lawton’s conjecture about the upper bound on themeasure of the set on the unit circle on which a complex polynomial with a bounded number of coefficients takes small values. Namely, we prove that Lawton’s bound holds for polynomials that are not necessarily monic. We also provide an analogous bound for polynomials in several variables. Finally, we investigate the dependence of the bound on the multiplicity of zeros for polynomials in one variable.
Atmospheric mercury concentrations observed at ground-based monitoring sites globally distributed in the framework of the GMOS network
Authors: Sprovieri Francesca , Pirrone Nicola , Bencardino Mariantonia , D'Amore Francesco , Carbone Francesco , Cinnirella Sergio , Mannarino Valentino , Landis Matthew , Ebinghaus Ralf , Weigelt Andreas , Brunke Ernst-Günther , Labuschagne Casper , Martin Lynwill , Munthe John , Wängberg Ingvar , Artaxo Paulo , Morais Fernando , Barbosa Henrique de Melo Jorge , Brito Joel , Cairns Warren , Barbante Carlo , Diéguez María del Carmen , Garcia Patricia Elizabeth , Dommergue Aurélien , Angot Helene , Magand Olivier , Skov Henrik , Horvat Milena , Kotnik Jože , Read Katie Alana , Neves Luis Mendes , Gawlik Bernd Manfred , Sena Fabrizio , Mashyanov Nikolay , Obolkin Vladimir , Wip Dennis , Feng Xin Bin , Zhang Hui , Fu Xuewu , Ramachandran Ramesh , Cossa Daniel , Knoery Joël , Marusczak Nicolas , Nerentorp Michelle , Norstrom Claus
Published: September 2016

Abstract. Long-term monitoring of data of ambient mercury (Hg) on a global scale to assess its emission, transport, atmospheric chemistry, and deposition processes is vital to understanding the impact of Hg pollution on the environment. The Global Mercury Observation System (GMOS) project was funded by the European Commission (http://www.gmos.eu) and started in November 2010 with the overall goal to develop a coordinated global observing system to monitor Hg on a global scale, including a large network of ground-based monitoring stations, ad hoc periodic oceanographic cruises and measurement flights in the lower and upper troposphere as well as in the lower stratosphere. To date, more than 40 ground-based monitoring sites constitute the global network covering many regions where little to no observational data were available before GMOS. This work presents atmospheric Hg concentrations recorded worldwide in the framework of the GMOS project (2010–2015), analyzing Hg measurement results in terms of temporal trends, seasonality and comparability within the network. Major findings highlighted in this paper include a clear gradient of Hg concentrations between the Northern and Southern hemispheres, confirming that the gradient observed is mostly driven by local and regional sources, which can be anthropogenic, natural or a combination of both.
Quantifying ice loss in the eastern Himalayas since 1974 using declassified spy satellite imagery
Authors: Maurer Joshua M. , Rupper Summer B. , Schaefer Joerg M.
Published: September 2016

Abstract. Himalayan glaciers are important natural resources and climate indicators for densely populated regions in Asia. Remote sensing methods are vital for evaluating glacier response to changing climate over the vast and rugged Himalayan region, yet many platforms capable of glacier mass balance quantification are somewhat temporally limited due to typical glacier response times. We here rely on declassified spy satellite imagery and ASTER data to quantify surface lowering, ice volume change, and geodetic mass balance during 1974–2006 for glaciers in the eastern Himalayas, centered on the Bhutan–China border. The wide range of glacier types allows for the first mass balance comparison between clean, debris, and lake-terminating (calving) glaciers in the region. Measured glaciers show significant ice loss, with an estimated mean annual geodetic mass balance of −0.13 ± 0.06 m w.e. yr−1 (meters of water equivalent per year) for 10 clean-ice glaciers, −0.19 ± 0.11 m w.e. yr−1 for 5 debris-covered glaciers, −0.28 ± 0.10 m w.e. yr−1 for 6 calving glaciers, and −0.17 ± 0.05 m w.e. yr−1 for all glaciers combined. Contrasting hypsometries along with melt pond, ice cliff, and englacial conduit mechanisms result in statistically similar mass balance values for both clean-ice and debris-covered glacier groups. Calving glaciers comprise 18 % (66 km2) of the glacierized area yet have contributed 30 % (−0.7 km3) to the total ice volume loss, highlighting the growing relevance of proglacial lake formation and associated calving for the future ice mass budget of the Himalayas as the number and size of glacial lakes increase.
CIKLINIŲ TRENIRUOČIŲ POVEIKIS PACIENTŲ, PATYRUSIŲ GALVOS SMEGENŲ INSULTĄ, EISENAI
Authors: Svirskis Donatas , Bartkienė Kristina , Būtėnaitė Lina
Published: September 2016

Tyrimo tikslas: palyginti skirtingo tipo ciklinių treniruočių efektyvumą pacientų, patyrusių galvos smegenų insultą, ėjimo funkcijai. Tyrimas atliktas 2014 - 2016 metais Vilniaus universiteto ligoninės Santariškių klinikų Reabilitacijos, fizinės ir sporto medicinos centre, II stacionarinės reabilitacijos skyriuje. Tyrime dalyvavo 28 pacientai: 15 vyrų (54%) ir 13 moterų (46%), patyrusių galvos smegenų insultą. Pacientai, atitinkantys įtraukimo į tyrimą kriterijus, atsitiktinės atrankos būdu suskirstyti į dvi grupes. Pacientų ištyrimas buvo atliekamas 2 kartus: pirmasis - atvykus į reabilitaciją, antrasis - baigus 15 ciklinių treniruočių programą. I grupės tiriamieji atliko ciklines treniruotes veloergometru Monark. II grupės tiriamieji atliko ciklines treniruotes ėjimo takeliu Biodex Gait Trainer 2. Be ciklinių treniruočių visi tiriamieji atliko įprastas individualiai pritaikytas funkcines ir bazines kineziterapijos procedūras, kurių metu nebuvo taikomos jokios papildomos ciklinės treniruotės. Pacientų eisena buvo vertinama: 10 metrų ėjimo testu, 6 minučių ėjimo testu, atliktas žingnsio ilgių sveikąja ir pažeista koja matavimas. Rezultatai. Tyrimo metu statistiškai reikšmingai padidėjo abiejų grupių pacientų ėjimo greitis, nueinamas atstumas per 6 minutes ir pažeistos kojos žingnsio ilgis (p<0,05). Sveikosios kojos žingsnio ilgis statistiškai reikšmingai (p<0,05) pakito tik II tiriamosios grupės pacientams. Tiriamųjų ėjimo greitis, nueinamas atstumas ir žingsnio ilgiai sveikąja ir pažeista koja po tyrimo statistiškai reikšmingai nesiskyrė (p>0,05). Vertinant pacientų ėjimo greičio pokytį procentine išraiška gautas statistiškai reikšmingas (p<0,05) skirtumas, rodantis didesnį pacientų ėjimo greičio padidėjimą II tiriamųjų grupėje. Nustatyta, kad nueinamo atstumo per 6 minutes pokytis statistiškai reikšmingai (p<0,05) buvo didesnis II tiriamųjų grupėje. Žingsnio ilgio sveikąja koja pokytis buvo statistiškai reikšmingai didesnis II tiriamųjų grupėje. Išvados. Nustatyta, kad taikant ciklines treniruotes veloergometru ir ėjimo takeliu statistiškai reikšmingai pagerėjo ėjimo greitis, nueinamas atstumas per 6 minutes, bei žingsnio ilgis pažeista koja. Žingnsio ilgio sveikąja koja statistiškai reikšmingas padidėjimas buvo stebimas pacientų, atlikusių ciklines treniruotes ėjimo takeliu, grupėje. Lyginant rezultatų pokyčius nustatyta, kad ciklinės treniruotės atliekamos ėjimo takeliu efektyviau pagerina pacientų, patyrusių galvos smegenų insultą, ėjimo greitį, nueinamą atstumą ir žingsnio ilgį sveikąja koja, nei ciklinės treniruotės atliekamos veloergometru.
KOORDINACIJOS IR PUSIAUSVYROS PRATIMAI PAGERINA SENYVO AMŽIAUS ASMENŲ NE TIK FUNKCINĮ PAJĖGUMĄ, BET IR KOGNITYVINES FUNKCIJAS
Authors: Muntianaitė Inga , Blužaitė Fausta , Indriūnienė Jurga , Žilinskienė Ramunė , Nainaitė Akvilė
Published: September 2016

Tyrimo tikslas: nustatyti taikomosios fizinės veiklos, pagrįstos koordinacijos ir pusiausvyros pratimais, poveikį senyvo amžiaus asmenų funkciniam pajėgumui ir kognityvinėms funkcijoms. Tiriamųjų kontingentas: tyrime dalyvavo 40 vyresnio amžiaus asmenų, kurių amžiaus vidurkis buvo 71,6 ± 6,9 metai. Tiriamieji buvo suskirstyti į 2 grupes: tiriamąją – mankštos grupę (n = 20; amžius 71,35 ± 6,52) ir kontrolinę – nesimankštinančiųjų grupę (n = 20; 73,55±5,47 metai). Tiriamajai grupei 8 savaites buvo taikoma fizinės veiklos programa, parengta pusiausvyros ir koordinacijos lavinimo tikslais. Užsiėmimai vyko 2 kartus per savaitę, trukmė 40 – 50 min. Tyrimo metodai: trumpasis fizinės funkcijos testų rinkinys, 5 žodžių testas, skaičių sujungimo testas, objektyvus (bendrasis) pažintinių funkcijų testas, subjektyvus pažintinių funkcijų testas, statistinė duomenų analizė. Rezultatai ir išvados: po pusiausvyros ir koordinacijos lavinimo programos tiriamosios grupės funkcinio pajėgumo rezultatai statistiškai reikšmingai pagerėjo ir skyrėsi nuo kontrolinės grupės (p<0,05): tiriamosios grupės bendra Trumpojo fizinės funkcijos testų rinkinio balų suma antro tyrimo metu buvo 11,80 ± 1,06 balų, kontrolinės grupės - 8,95 ± 1,15 balo (p<0,05). Tiriamosios grupės objektyvus ir subjektyvus kognityvinių funkcijų lygis pagerėjo labiau nei kontrolinės grupės (p<0,05); tiriamosios grupės dalyvių trumpalaikės atminties ir ilgalaikės atminties rezultatai II tyrimo metu buvo geresni nei kontrolinės grupės (p<0,05). Tiriamosios grupės vykdomųjų kognityvinių funkcijų rezultatai, po pusiausvyros ir koordinacijos lavinimo programos, statistiškai reikšmingai pagerėjo, tačiau tarp grupių nesiskyrė (p=0,074). Išanalizuoti atlikto tyrimo duomenys rodo, jog taikomosios fizinės veiklos programa, parengta pusiausvyros ir koordinacijos tikslais, daro teigiamą poveikį senyvo amžiaus asmenų funkciniam pajėgumui ir kognityvinėms funkcijoms.
POSSIBILIDADES DA PSICOLOGIA NO ENSINO MÉDIO: UMA PROPOSTA DE ORIENTAÇÃO PROFISSIONAL
Authors: Larissa Ferrari Becker Jessica , De Araújo Tatiely Pereira
Published: September 2016

Este trabalho refere-se a um subprojeto do Programa Institucional de Bolsa de Iniciação à Docência Pibid, do curso de Psicologia da Universidade Federal de Goiás, Campus Goiânia. O projeto de Orientação Profissional, baseado na abordagem histórico-cultural, foi realizado em um Colégio Estadual de Ensino Médio de Goiânia, na disciplina Projeto de Vida. Tivemos como objetivo desenvolver debates e provocar reflexões nos alunos a respeito dos processos relacionados à escolha profissional. Para alcançar este objetivo o projeto foi desenvolvido em três unidades: módulo 1 – Autoconhecimento e o Significado da Escolha Profissional; módulo 2 – Os Determinantes da Escolha Profissional; módulo 3 – Informação Profissional. As aulas foram ministradas em quatro turmas de alunos dos segundos anos uma vez por semana, 50 minutos por aula. A metodologia mais utilizada foi de aula expositiva-dialogada, embora tenha havido também projeção do filme “Divergente”, músicas e vídeos. Ao final da realização do projeto, acreditamos que a experiência foi muito válida, pois foi possível perceber a mudança nos paradigmas através da fala dos próprios alunos: passaram a analisar as multideterminações envolvidas em um processo de escolha; conhecer mais e melhor diversas profissões e o percurso necessário para se chegar até ela, etc. Para nós licenciados, a experiência também se mostrou bastante formativa, pois permitiu a aproximação do aluno de Psicologia com o Ensino Médio. Portanto, nos fez repensar criticamente as contribuições que a Psicologia poderia oferecer a essa etapa da educação básica, caso fosse inserida no currículo das escolas de Ensino Médio.