bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flexural rigidity, curvature and rotation and their significance in reinforced concrete design
Authors: Burnett E. 
Published: July 2012

Summary Some of the more fundamental and possibly less familiar aspects of current ultimate load theory are discussed, the behaviour of the simply supported under-reinforced concrete beam being used for illustration. The generalized relations between bending moment and curvature, and bending moment and rotation are given. The value of the mean flexural rigidity of the member is derived and compared with other possible values. The concept of the plastic hinge and the significance of elastic and inelastic contributions to the over-all deformation of the member are discussed.
Upper and lower bound solutions to the collapse of a continuous slab under uniform load
Authors: Holmes M. , Steel K. A. 
Published: July 2012

Summary Upper bound solutions to the collapse of continuous slabs may be calculated by applying the yield-line theory, but corresponding lower bound solutions are not available. R. H. Wood has discussed this lack of knowledge of lower bound or safe solutions. In the present paper, a lower bound solution to the collapse of a uniformly loaded isotropically reinforced rectangular slab, with two opposite sides continuous and the other sides simply supported, is developed. This solution is compared with the upper bound values, over a wide range of values for the ratio of the sides of the slab, and the agreement is shown to be within 8%. The solution is used to determine the distribution of moments in the slab and the loads transmitted to the perimeter beams.
The effect of grout properties on transmission length in grout-bonded post-tensioned concrete beams
Authors: Geddes J. D. , Soroka I. 
Published: July 2012

Summary The effect of the quality of grouts on transmission lengths observed after the release of one of the mechanical anchorages was investigated by tests on nineteen grout-bonded post-tensioned concrete beams. The results showed that the transmission lengths for this condition were directly related to the compressive strengths of the grouts used. Grouts containing aluminium powder possess relatively high compressive strengths when expansion is restrained during setting, as in ducts, and consequently better bonding ability, and their use is therefore worthy of consideration.
The effect of the elastic modulus of the aggregate on the elastic modulus, creep and creep recovery of concrete
Authors: Counto Upendra J. 
Published: July 2012

Summary This paper discusses some of the models currently available for the prediction of the modulus of elasticity of concrete. A new model is proposed which gives a satisfactory prediction for a wide variety of aggregates and concrete mixes. The same model explains satisfactorily the isolated effect of the elastic modulus of the aggregate on the creep and creep recovery of concrete. In order to provide a critical test of this effect, experiments were carried out on concretes made with artificial aggregates having a large range of elastic moduli. Results of these experiments are presented. It is concluded that the elastic strain, creep and creep recovery of concrete increase as the elastic modulus of the aggregate decreases.
The ultimate strength and long-term behaviour of uniformly loaded, two-way concrete slabs with partial lateral restraint at all edges
Authors: Park R. 
Published: July 2012

Summary A theory for the ultimate flexural strength of uniformly loaded, laterally restrained two-way concrete slabs (reinforced or unreinforced) is extended to include the effect on the compressive membrane action of partial restraint against lateral displacement at all the edges and axial strains in the plane of the slab. The edges of the slab are considered to be fixed against rotation and vertical translation, and a strip approximation is used with an empirical value for the deflexion at ultimate load. The theory is applicable to the interior panels of slab-and-beam floors under short-term or sustained uniform loading. It is shown that partial lateral restraint and axial strains can reduce the compressive membrane action significantly, especially in the case of thin slabs. The theory is compared with the results obtained from eight unreinforced slabs tested under sustained uniform loading and is shown to give a conservative indication of the ultimate flexural strength in most cases.
The components of strain in concrete under sustained compressive stress
Authors: Illston J. M. 
Published: July 2012

Summary The strain of concrete under sustained compressive stress is examined in terms of three components, instantaneous recoverable, time-dependent recoverable and irrecoverable, defined here as elastic, delayed elastic and flow respectively. Experimental evidence is presented of the influence on each of the length of the period of loading and the age of the concrete when the load is applied. It was found that at a given age the rate of flow is virtually independent of any earlier loading and that the delayed elastic strain tends to a limiting value which varies little with the age of the concrete. The rate of occurrence of delayed elastic strain diminishes with the age of the concrete and it can be linked with the corresponding rate of flow.
Bulk storage of cement for a concrete laboratory
Authors: Lunt B. G. , van der Meulen G. J. R. 
Published: July 2012

Summary The paper describes a recently developed storage system using an air-tight welded-steel silo which discharges through a rotary-vane feeder and closed screw conveyor. The special precautions for preventing ingress of water and carbon dioxide and the facilities for fluidizing the cement are also covered in detail.
Using curvature of precast beams to measure the loss of prestress due to creep before loading
Authors: Davies R. D. 
Published: July 2012

Summary The loss of prestress due to creep before loading in small precast prestressed beams was calculated from their change of curvature. The results were checked by measuring the change in the lengths of the prestressing wires and the shrinkage of control pieces. An application of the idea to creep tests on compression specimens is mentioned.
Data on the binary system 3CaO.Al2O3-Na2O.8CaO.3 Al2O3 within the system CaO-Al2O3-Na2O
Authors: Fletcher K. E. , Midgley H. G. , Moore A. E. 
Published: July 2012

Summary Conwicke and Day showed that partial solid solution occurs in the system C3A-NC8A3 at temperatures below the liquidus. Their results indicated a marked similarity between the X-ray powder diffraction data for a preparation containing more than 3·0% Na2O and the data given by Moore for a new phase in Portland cements. The present work was almost complete when Conwicke and Day's paper was published. It generally confirms their results but gives more information on the solid solution. At the limit of solid solution at 1,350°C the sodium calcium aluminate which is formed has the composition 91·0 mol % C3A, 9·0 mol % N3A and has been indexed on an orthorhombic unit cell with a = 15·314, b = 15·394, c = 15·137 Å.
The optimum coarse aggregate content of concrete
Authors: Hughes B. P. 
Published: July 2012

Summary The best proportions in which to combine any given coarse andfine aggregates are considered with particular reference to concrete mix design. Earlier work, which was restricted to ¾ in. maximum size of aggregate and used the compacting factor test to indicate the workability of the concrete, is extended to ⅜ in maximum size of aggregate using the Vebe consistometer test. In addition to extending the range of the curves for use in mix design, the present work shows that the optimum specific volume ratio of coarse aggregate for the Vebe consistometer test is similar to that for the compacting factor test. This is a most important result since it shows that the application of the concept of particle interference is not restricted to the compacting factor test.
Tensile strains in unreinforced concrete beams
Authors: Welch G. B. 
Published: July 2012

Summary The behaviour of concretes and mortars subject to tensile strain was examined by measuring strains on the tension face of moist beam specimens during the standard flexural strength test. A wide range of concretes was examined with compressive strengths from 1,500 to more than 11,000 lb/in2 at 28 days. Initial cracking, as indicated by a significant deviation of the load-strain curve, was found to occur at tensile strains ranging from 41 to 158 × 10−6 for the range of concretes tested at 28 days. The corresponding average maximum tensile strains, measured before final crack propagation led to fracture, ranged from 75 to 240 × 10−6. These strains were affected by several factors but generally increased with increasing concrete strengths. The behaviour of mortars and concretes with high mortar content differed from that of normal concretes, and the tensile strains were much greater.
The influence of cement paste content on the creep of lightweight aggregate concrete
Authors: Rutledge S. E. , Neville A. M. 
Published: July 2012

Summary The paper is an extension to lightweight aggregate concrete of earlier work on the influence of cement paste content on the creep of concrete. It is shown that there is a simple relation between the creep after a given time under load and the content of cement paste corrected for unhydrated cement. An expression is proposed for the creep-time behaviour of concrete of any mix proportions but made with a given type of aggregate; this involves a total of four constants from two creep-time tests.
Determining the setting time of cement paste, mortar and concrete with a copper-lead electrode
Authors: Aschan Nils 
Published: July 2012

Summary The point at which the rate of hydration of the alite phase in clinker, which is very slow in the beginning, starts to accelerate and the cement paste begins to turn solid can be determined with a copper-lead electrode. This point is clearly indicated by the distinct increase of potential difference when the surface of copper oxidizes to cuprous oxide as air penetrates to the capillary space. Air dissolved in the mixing water does not cause oxidation, nor does entrained air present under practical working conditions. Because of the total absence of the disturbing influence of the aggregate, this method of determining the setting time of mortar or concrete is more accurate than the commonly used mechanical methods and it also yields results which better correspond to the actual situation. The reaction vessel need not be of any specific shape, and therefore direct placement of the electrode, for instance, in a unit mould is possible. In principle, this method is also applicable to hydraulic bonding agents other than Portland cements.
Is your research really necessary?
Authors: McIntosh J. D. 
Published: July 2012

Summary Recent events have indicated a growing concern about the effectiveness of research for the construction industry. These are reviewed, and provocative comments are offered, to stimulate a critical appraisal of the value of the subjects chosen for study. It is suggested that concrete research has tended to follow a traditional pattern, continuing to examine factors well into unrewarding regions according to the law of diminishing returns and ignoring areas which could have a major effect on the over-all cost of construction. This situation is attributed largely to the varied way in which the results of different types of investigation are received by the industry. The research worker is exhorted to spend more time in applying his critical faculties to examine how best he can serve the industry and in using his unbiased judgement to incorporate his findings into the common experience of the practitioners he serves.
The strength of concrete under combined shear and direct stress
Authors: Goode C. D. , Helmy M. A. 
Published: July 2012

Summary Thirty-nine hollow cylinders, made of five different concrete mixes, were tested under direct compression and torsion to study the failure of concrete under the ensuing biaxial state of stress. The results of these tests are compared with similar tests by other investigators and discussed in relation to various failure criteria.
Alkali reactivity of dolomitic limestone aggregate
Authors: Swenson E. G. , Gillott J. E. 
Published: July 2012

Summary Additional evidence was obtained in support of the hypothesis that excessive expansion in the alkali-carbonate rock reaction is caused by moisture uptake by the previously ‘unwetted clay’ constituent. The dedolomitization reaction is shown to be necessary only to provide access of moisture to the ‘locked-in’ clay. A microscopic method was used to determine the specific surface of the dolomitc, the quantitative nature of which made it possible to define a practical upper limit below which expansion does not occur. It was also shown that relatively small percentages of illitic clay can account for the excessive expansion shown by reactive carbonate rocks. The new techniques used included measurements of dimensional change of thin rock wafers and of compacts of clay and powdered rock.
A mathematical model for the failure of cement paste and mortars
Authors: Dougill John W. 
Published: July 2012

Summary It is suggested that structural models have only a limited use in a study of failure and an alternative mathematical model is proposed which behaves, in many ways, like hardened cement paste or mortar. The model is similar to Volkov's normal micro-inhomogeneous material, the major difference being in the failure criteria used at the microscopic level. The behaviour of the model material in simple tension is studied and it is shown that progressive fracture, or micro-cracking, occurs during all stages of loading. The mode of failure depends upon the method of test because either the material fails when the maximum stress is reached or progressive fracture continues with increased deformation and a reduction in applied stress. In addition, a ductile mode of failure is investigated and it appears that, in contrast to brittle fracture, the ultimate strength may be almost unaffected by micro-inhomogeneity.
An analysis of the creep and shrinkage effects upon prestressed concrete members under temperature gradient and its application
Authors: Arthanari S. , Yu C. W. 
Published: July 2012

Summary The influence of differential creep and shrinkage upon prestressed concrete ring structures is discussed. Expressions have been developed for finding the variation of stress and strain with time in a flexurally restrained prestressed concrete beam subjected to temperature gradient. It has been concluded that the creep phenomena can be used to the best advantage by pre-heating such structures.
Effect of Hydrosoluble Chlorine–Mediated Antimicrobial Photodynamic Therapy on Clinical Parameters and Cytokine Profile in Ligature‐Induced Periodontitis in Dogs
Authors: Sorkhdini Parand , Moslemi Neda , Jamshidi Shahram , Jamali Raika , Amirzargar Ali Akbar , Fekrazad Reza 
Published: July 2012

Background: Recently, a hydrosoluble chlorine composed of sodium salts chlorine e6, chlorine p6, and purpurine‐5 has been shown to be a promising photosensitizer in antimicrobial photodynamic therapy (aPDT). The aim of this study is to evaluate the effects of adjunctive application of hydrosoluble chlorine–mediated aPDT compared with scaling and root planing (SRP) alone on clinical parameters and cytokine levels in gingival crevicular fluid of dogs with experimental periodontitis.Methods: Periodontal disease was induced by placing silk ligatures around both maxillary and mandibular teeth. After establishment of attachment loss, full‐mouth SRP was performed in all dogs. One day after SRP, each quadrant randomly received one of the following treatment modalities: hydrosoluble chlorine plus diode laser (wavelength 662 nm, power 100 mW, continuous mode, time of irradiation 20 seconds), hydrosoluble chlorine alone, laser alone, or no adjunctive treatment. The same adjunctive procedure was repeated 1 week later. Clinical parameters including periodontal probing depth, clinical attachment level, and bleeding on probing, as well as crevicular levels of interleukin‐1β and tumor necrosis factor‐α, were evaluated at baseline, at 3 weeks, and at 3 months after treatment.Results: After both 3 weeks and 3 months, all treatment groups showed significant improvement in all clinical and immunologic parameters (P <0.001). No significant differences were found between the four groups with regard to the measured parameters (P >0.05).Conclusion: Based on the results of this study, adjunctive use of hydrosoluble chlorine–mediated aPDT with the current setting has no additional effect on the clinical parameters or proinflammatory cytokine levels in ligature‐induced periodontitis.
Trends in Michigan Early Adolescent Immunization: 2006–2008
Authors: Rees-Clayton Erin , Montgomery JoLynn P. , Enger Kyle S. , Boulton Matthew L. 
Published: July 2012

Objectives. We have described vaccine coverage of Michigan young adolescents immunized with tetanus, diphtheria, and pertussis; meningococcal conjugate; and human papillomavirus vaccines during 2006–2008. Methods. We obtained data from the Michigan Care Improvement Registry, a state-based immunization information system that included more than 57 million vaccination records. We examined 3 overlapping cohorts of 11- and 12-year-old children (n > 350 000 in each) to assess temporal trends in vaccination coverage, characteristics of those immunized, funding sources, and vaccination sites. Results. Vaccine uptake increased during 2006 through 2008, peaking in the summer months. More than half of children receiving more than 1 vaccine received the vaccines simultaneously. Older age, receipt of Medicaid, and prior completion of early childhood immunizations were associated with greater odds of vaccination. Conclusions. Vaccine coverage among Michigan young adolescents is increasing but continues to be relatively low. Coverage of 11- and 12-year-old children may improve with efforts to encourage vaccination at all health care visits, an increase in public funding in support of adolescent vaccination, and continued monitoring of adolescent vaccination levels through school-based assessments.
Urinary calculi — atypical source of information on mercury in human biomonitoring
Authors: Kuta Jan , Machát Jiří , Benová Daniela , Červenka Rostislav , Kořistková Tamara 
Published: July 2012

Abstract
Chemical analysis of various biological matrices is routinely used for assessment of human exposure to various toxic metals. In this work, 489 samples of urinary calculi originating from almost the whole of The Czech Republic, were collected and subjected to mineralogical and elemental analysis. This study was aimed at mercury, the content of which was determined using thermo-oxidation — cold vapor — atomic absorption spectrometry. The effects of mineralogical composition, sex, age and region were recorded in order to verify the applicability of urinary calculi for biomonitoring. Relationships with other minor and trace elements were also investigated. Association of mercury with whewellite mineral was observed as well as a remarkable relationship with selenium, confirming the role of selenium in mercury excretion. No statistically significant effect was observed on the mercury content in stones with regard to the sex or region. Median values in age groups follow a trend with the maximum median value 0.365 mg kg−1 in the group of 41–50 year old donors, decreasing to 0.060 mg kg−1 for the oldest group (81–92 years). Our results confirm that urinary calculi can be helpful in providing complementary information on human exposure to mercury and its excretion.
Characterization of calcium carbonates used in wet flue gas desulphurization processes
Authors: Dragan Simion , Ozunu Alexandru 
Published: July 2012

Abstract
This paper presents an experimental characterization of two sources of calcium carbonate, limestone and calcium carbonate precipitate (CCP) used in wet flue gas desulphurization processes. Characterization of the two carbonate sources was carried out by chemical analysis, IR spectra, thermal behavior, particle size distribution for CCP, BET surface area and absorption capacity of SO2 in calcium carbonate suspensions. The absorption temperature, suspension concentration and carbonate grain size were found to be the most influential parameters in the absorption capacity measurements.
Immobilization of quaternary ammonium salts on silica gel for perchlorate ions removal
Authors: Kurczewska Joanna , Pankiewicz Radosław , Schroeder Grzegorz 
Published: July 2012

Abstract
Silica surface was modified with quaternary ammonium salts to give three matrices of different chain length. The synthesized supports were characterized by elemental analysis and infrared spectroscopy, as well as scanning electron microscopy and semi-empirical parametric method 5. Their exchange capacities for ClO4−, F−, NO3− and CH3COO− ions were investigated by conductometric titration. The amount of exchanged chloride ions from the matrix was studied for different initial anions concentration. The functionalized silica gel showed very good ability of perchlorate ions exchange from the water solution in room temperature. The anion-exchange properties were also studied in comparison to different number of reactive sites in the matrices. The increased number of chloride at the silica surface took effect on increased ability of ClO4− anion exchange
Sol-gel synthesis and study of neodymium substitution effects in Co-Al-Nd-O system with possible applications as novel inorganic pigments
Authors: Jonynaite Dalia , Jasaitis Darius , Raudonis Rimantas , Selskis Algirdas , Juskenas Remigijus , Senvaitiene Jurate , Kareiva Aivaras 
Published: July 2012

Abstract
In the present work, the formation of cobalt aluminium spinel (CoAl2O4) as well as novel cobalt neodymium-aluminates with nominal compositions of CoAl1.75Nd0.25O4, CoAl1.5Nd0.5O4 and CoAlNdO4 by an aqueous sol-gel process and the sinterability of the products are investigated. The metal ions, generated by dissolving starting materials of metals in the diluted acetic acid were complexed by 1,2-ethanediol to obtain the precursors for the mixed metal ceramics. The phase purity of the synthesized compounds was characterized by powder X-ray diffraction analysis and infrared spectroscopy. The microstructural evolution and morphological features of the products were studied by scanning electron microscopy and atomic force microscopy, which together with the optical characterization of these new compounds showed that the sol-gel-derived materials could be successfully used as effective cobalt-based ceramic pigments.
Spontaneous oscillations due to solutal Marangoni instability: air/water interface
Authors: Kovalchuk Nina 
Published: July 2012

Abstract
Systems far from equilibrium are able to self-organize and often demonstrate the formation of a large variety of dissipative structures. In systems with free liquid interfaces, self-organization is frequently associated with Marangoni instability. The development of solutal Marangoni instability can have specific features depending on the properties of adsorbed surfactant monolayer. Here we discuss a general approach to describe solutal Marangoni instability and review in details the recent experimental and theoretical results for a system where the specific properties of adsorbed layers are crucial for the observed dynamic regimes. In this system, Marangoni instability is a result of surfactant transfer from a small droplet located in the bulk of water to air/water interface. Various dynamic regimes, such as quasi-steady convection with a monotonous decrease of surface tension, spontaneous oscillations of surface tension, or their combination, are predicted by numerical simulations and observed experimentally. The particular dynamic regime and oscillation characteristics depend on the surfactant properties and the system aspect ratio.