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Article
Publication date: 1 February 2002

R. Romagnoli, R.O. Batic, V.F. Vetere, J.D. Sota, I.T. Lucchini and R.O. Carbonari

Hardened cement paste is a heterogeneous system resulting from the grouping of particles, films, microcrystals and other solid structural elements bounded in a porous mass. The…

998

Abstract

Hardened cement paste is a heterogeneous system resulting from the grouping of particles, films, microcrystals and other solid structural elements bounded in a porous mass. The cement paste microstructure must be understood firstly due to its influence on concrete properties. The behaviour of concrete greatly depends on the conformation of localised special structures rather than on general structures found in the mass cement paste. The objective of this paper was to study the cement paste microstructure, as a function of the water–cement ratio, in order to interpret the variations of the steel–mortar bond strength and the developing of the corrosion process in steel–mortar specimens kept in tap water and 3 percent sodium chloride solutions for 1 year. A description of the steel–mortar interface was also provided.

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Anti-Corrosion Methods and Materials, vol. 49 no. 1
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 4 January 2013

O.R. Batic, J.D. Sota, J.L. Fernández, N. Bellotti and R. Romagnoli

This research aims to study the influence of limestone filler on rebar corrosion.

307

Abstract

Purpose

This research aims to study the influence of limestone filler on rebar corrosion.

Design/methodology/approach

Mortar samples containing 35% calcareous filler and with a rebar inserted in the axis, were cast. Specimens were cured at the open air and during 28 days in lime water. After curing, they were submerged in two electrolytes (tap water and 3% NaCl) and corrosion parameters (corrosion potential and corrosion current) were monitored over time by d.c. techniques. Simultaneously, electrochemical noise measurements were carried out. After corrosion tests, rebars were pulled out by lateral compression, and their surface observed by scanning electron microscopy.

Findings

In general, carbonate additions impaired mortar protective properties, especially in the presence of chloride and changed the nature of the protective layer on rebars. The curing process did not introduce significant differences except for mortars with a high water cement ratio cured in lime water for which the beneficial effects of the simultaneous presence of carbonate and lime in the pore solution could be appreciated. The role of carbonate additions is to provide carbonate anions to passivate rebars. This passivation process caused corrosion rates not to be so high. Carbonate anions also deposited on oxide spots which were rendered passive but this process was not uniform. Certain areas on the rebar underwent intense carbonation while others showed increased corrosion rates.

Originality/value

There are not many corrosion studies about the influence of limestone filler on rebars corrosion. Particularly, this paper deals with mortars containing high percentages of carbonate additions. Results showed that the presence of this type of admixture changes the structure of the passive layer and, sometimes, may increase corrosion rates.

Details

Anti-Corrosion Methods and Materials, vol. 60 no. 1
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 April 1992

S. BRANDON and J.J. DERBY

A finite element method for the analysis of combined radiative and conductive heat transport in a finite axisymmetric configuration is presented. The appropriate…

131

Abstract

A finite element method for the analysis of combined radiative and conductive heat transport in a finite axisymmetric configuration is presented. The appropriate integro‐differential governing equations for a grey and non‐scattering medium with grey and diffuse walls are developed and solved for several model problems. We consider axisymmetric, cylindrical geometries with top and bottom boundaries of arbitrary convex shape. The method is accurate for media of any optical thickness and is capable of handling a wide array of axisymmetric geometries and boundary conditions. Several techniques are presented to reduce computational overhead, such as employing a Swartz‐Wendroff approximation and cut‐off criteria for evaluating radiation integrals. The method is successfully tested against several cases from the literature and is applied to some additional example problems to demonstrate its versatility. Solution of a free‐boundary, combined‐mode heat transfer problem representing the solidification of a semitransparent material, the Bridgman growth of an yttrium aluminium garnet (YAG) crystal, demonstrates the utility of this method for analysis of a complex materials processing system. The method is suitable for application to other research areas, such as the study of glass processing and the design of combustion furnace systems.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 2 no. 4
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 November 1949

T. Tonkin

Type: Composite construction, strut braced, high wing mono‐plane.

49

Abstract

Type: Composite construction, strut braced, high wing mono‐plane.

Details

Aircraft Engineering and Aerospace Technology, vol. 21 no. 11
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 May 2010

Ibrahim A. Hassan

Potato (Solanum tuberosum L. cv. Kara) was grown in Open‐Top Chambers (OTCs) in Northern Egypt at ambient (ca 350 ppm) or doubled CO2 (ca 690 ppm) either in charcoal‐filtered air…

181

Abstract

Potato (Solanum tuberosum L. cv. Kara) was grown in Open‐Top Chambers (OTCs) in Northern Egypt at ambient (ca 350 ppm) or doubled CO2 (ca 690 ppm) either in charcoal‐filtered air (15 nl l‐1) or in non‐filtered ambient air (78 nll‐1 O3) to investigate the changes in physiology and yield under long‐term elevated CO2 and/or O3 throughout 100 days. Ambient O3 level reduced net photosynthetic rates, number and weight of tubers by 18 per cent, 41 per cent and 21 per cent, respectively, whereas elevated CO2 caused the opposite effect where it increased the same parameters by 44 per cent, 37 per cent and 20 per cent, respectively. Significant O3 x CO2 interactions were detected. However, O3 caused an increase in GR and POD by 18 per cent and 35 per cent, respectively, while CO2 caused an increase in POD only by 46 per cent, and there was no effect of O3 and/or CO2 on other enzymes. The results of this study are discussed in relation to predicted atmospheric changes.

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World Journal of Science, Technology and Sustainable Development, vol. 7 no. 2
Type: Research Article
ISSN: 2042-5945

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Article
Publication date: 1 January 1996

Boyd, Brown & Co. has come up with a new way to manage your risk if your business is international trade. Risk‐Transfer, the trademarked financial product it developed in…

53

Abstract

Boyd, Brown & Co. has come up with a new way to manage your risk if your business is international trade. Risk‐Transfer, the trademarked financial product it developed in partnership with Chubb Insurance as the underwriter, protects the financing of purchase orders for import, export, and domestic trade transactions by covering them with proprietary specification compliance insurance.

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Journal of Business Strategy, vol. 17 no. 1
Type: Research Article
ISSN: 0275-6668

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Article
Publication date: 1 October 1954

B.R. Noton

EACH September the eyes of the aeronautical World turn towards the S.B.A.C. Air Display and Exhibition with interest unequalled by any other event. It is fitting that the Display…

66

Abstract

EACH September the eyes of the aeronautical World turn towards the S.B.A.C. Air Display and Exhibition with interest unequalled by any other event. It is fitting that the Display is now held each year at the airfield of the Royal Aircraft Establishment, one of the world's most prominent aeronautical research centres. This interest becomes increasingly keen too, as the preview day comes closer, because new prototypes of unorthodox designs often appear a short time before the Show to illustrate the results of years of careful planning, development and research of the particular company. These designs often mould the path of progress for smaller countries without the economic resources to forge the way ahead alone. Most British citizens are very proud of their country's place in aviation today, both in the military and civil fields. This is understood by most foreigners because it is clear that Britain has won a place in aeronautical development second to none.

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Aircraft Engineering and Aerospace Technology, vol. 26 no. 10
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 October 1952

F.E. Osborne

AT temperatures commonly attained in the reaction of liquid propellents at operative pressures in rocket combustion chambers, the significant gaseous end products can be shown to…

28

Abstract

AT temperatures commonly attained in the reaction of liquid propellents at operative pressures in rocket combustion chambers, the significant gaseous end products can be shown to consist at chemical equilibrium of some or all of the following types: H2O, CO2, N2, CO, H2, O2, OH, NO, H, O, N and (rarely) C‐gaseous. The concentrations of these constituents are dependent, for a given propellent combination, upon the temperature (and to a less extent the pressure) conditions under which the reaction proceeds to equilibrium. Thus at temperatures below 2,500°K., the products H2O, CO2, N2 alone are of significance for the case of oxygen balance, whilst to these are added O2 for the oxygen excess case, and CO and H2 for oxygen deficit. The other products are formed by dissociation of these, and their concentrations increase sharply as the temperature rises above some 2,700°K.

Details

Aircraft Engineering and Aerospace Technology, vol. 24 no. 10
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 June 1976

A NEW word is being thrown at management from every direction. It is Participation. Just what does it mean, what does it entail? To many board members it means little but a…

56

Abstract

A NEW word is being thrown at management from every direction. It is Participation. Just what does it mean, what does it entail? To many board members it means little but a confounded nuisance. Not only in private or public companies; also some of the nationalised industries To workers it can mean many different things: the realisation of a dream; or a nightmare. For the fact must be faced: participation in management and direction must entail participation in responsibility. So it is sharing blame as well as grabbing credit. Unfortunately even apportioning blame doesn't keep a sinking company afloat; and the end result is the same whether the inexpert direction came from one end of the industry or the other. Inefficiency has to be paid for by bitter experience.

Details

Work Study, vol. 25 no. 6
Type: Research Article
ISSN: 0043-8022

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Article
Publication date: 1 October 1931

W.G. Jennings

WING tip automatic slots have proved an effective device for providing increased lateral stability at the stall and many service aircraft of the two seater and larger types have…

21

Abstract

WING tip automatic slots have proved an effective device for providing increased lateral stability at the stall and many service aircraft of the two seater and larger types have been fitted with them. In the case of single seater fighter aircraft, where manoeuvrability is of primary importance, it is desirable that adequate control at the stall should also be provided and the plain automatic slot does not, in general, supply this need. Certain aircraft fitted with the interconnected slot and aileron type control have shown satisfactory control characteristics at the stall but little or no increase in stability.

Details

Aircraft Engineering and Aerospace Technology, vol. 3 no. 10
Type: Research Article
ISSN: 0002-2667

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