properties of concrete for use in eurocode 2 135 (original) (raw)
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Contract Specifications for Durable Concrete Structures
Concrete meets the needs of sustainability in terms of economic, environmental and social considerations. The material intrinsically offers a wide range of the following benefits, viz., acoustics, vibration, fire, thermal mass, durability, security, sustainability, air tightness, and flood resistance. The vast majority of concrete structures throughout the world have performed satisfactorily for many years but progress has not been made without its problems. Over the years the quality control has deteriorated arising out of use of poor quality ingredients, uncontrolled use of water both in terms of quality and quantity, poor quality shuttering, poor or no compaction and inadequate curing. There is also deterioration in the level of standard skill among the Artisans as well as among those, who supervise and accept the works. While the older structures are able to serve adequately, the recent constructions are showing signs of distress in a couple of years of their completion. It is high time that deep attention is paid to the basic issues more seriously. At present attention is mainly focussed on environmental attack, which is substantially reducing the lives of many concrete structures around the world, in many cases due to the corrosion of reinforcement steel. Deterioration of concrete structures constructed in recent times is observed at relatively faster rates, and has been mainly attributed to cracking. Cracking is associated with the use of faster-hydrating Portland cements with increased fineness and the tricalcium silicate (C3S) content to support the high speed of modern construction.
CHAPTER – I INTRODUCTION TO CONCRETE AND CONCRETE MATERIALS
These days, there are two commonly used structural materials: concrete and steel. They sometimes complement one another, and sometimes compete with one another, so that many structures of a similar type and function can be built in either of these materials. And yet, universities, polytechnics and colleges teach much less about concrete than about steel. This in itself would not matter were it not for the fact that, in actual practice, the man on the job needs to know more about concrete than about steel." --Concrete Technology (A. M. Neville CBE, J. J. Brooks)
Compliance criteria for quality concrete
Construction and Building Materials, 2008
With the advancement in cement technology, it is now possible to produce concrete of high strength with increased water/cement ratio. While this may satisfy the strength requirement, it is possible that the durability of such concrete is despaired. Though international organizations specify minimum cementititous materials content and maximum water/cementititous materials ratio, the quality assessment parameter is still the compressive strength. There is, however, a need to switch to permeability or chloride diffusion indices to ascertain the quality concrete. At the same time, compliance criteria for the present-day concrete need to be developed. In the reported study, an extensive experimental work was carried out to assess the compressive strength development, depth of water penetration and chloride permeability of plain, silica fume and fly ash cement concretes prepared with varying mixture proportions. The experimental data were utilized to develop statistical relationship between the mixture design parameters and the strength and durability indices. These data were also utilized to develop quality compliance criteria for concrete prepared with the crushed limestone aggregates.
DESCRIPTION. The aim of Cement and Concrete Research is to publish the best research on cement, cement composites, concrete and other allied materials that incorporate cement. In doing so, the journal will present: the results of research on the properties and performance of cement and concrete; novel experimental techniques; the latest analytical and modelling methods; the examination and the diagnosis of real cement and concrete structures; and the potential for improved materials. The fields which the journal aims to cover are: • Processing: Cement manufacture, mixing and rheology, admixtures and hydration. While the majority of articles will be concerned with Portland cements, we encourage articles on other cement systems, such as calcium aluminate. • Structural and Microstructural Characterisation of the unhydrated components and of hydrated systems including: the chemistry, crystal structure, pore structure of cement and concrete, characterisation techniques, and structural and microstructural modelling. • The properties of cement and concrete, including: fundamental physical properties; transport, mechanical and other properties, the processes of degradation of cement and concrete; and the modelling of properties, both as a means of predicting short and long performance, and as a means of relating a material's structure to its properties. • Applications for cement and concrete, including: concrete technology, fibre reinforcement, waste management, and novel concretes. The journal's principal publications are original articles containing new information, major reviews and selected papers from important conferences. Discussion of published material and rapid communications will form part of the journal where appropriate. The journal will focus on papers with a broad interest, based upon their subject area, the quality of the research, the novelty of the results and the potential for assimilation of the findings.
Specification for Tolerances for Concrete Construction and Materials and Commentary
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