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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 31 Abstracts search results
Document:
SP144-26
Date:
March 1, 1994
Author(s):
O. E. Gjorv
Publication:
Symposium Papers
Volume:
144
Abstract:
To insure adequate durability and long-term performance of reinforced concrete structures exposed to aggressive environments, relevant quality parameters are needed that can provide a better basis for job specification and control of in situ quality. The
DOI:
10.14359/884
SP144-21
S. Mindess and N. Banthia
In current construction practice, discontinuous fibers are added to cementitious matrices at relatively low volume fractions (usually < 1 .O%), mostly in order to improve the toughness, or the post-cracking ductility, of the composite. At these addition rates, there is relatively little improvement in strength. Moreover, there are no generally accepted methods of characterizing the improvements in other mechanical properties which the fibers may impart to the concrete. As a result, the various national structural design codes do not recognize fiber reinforced concrete (FRC) as a distinct material, and this inhibits its use in structural applications. However, there is continued research on the use of fibers in conjunction with conventional continuous steel reinforcement to improve the structural behaviour of concrete. In addition, a new generation of micro-fibers is being developed, which can be used at higher addition rates to bring about major improvements in the mechanical properties of FRC. In this review, current FRC technology is described. Likely future developments of FRC are also considered, such as applications in the design of concrete structures subjected to dynamic (blast, impact or earthquake) loading. The next generation of FRC materials will have the capacity of being tailored for a wide range of specific applications, and should be able to compete with other structural materials in a variety of applications.
10.14359/10047
SP144-18
D. M. Roy and M. R. Silsbee
Novel cements used in the making of very strong or otherwise high-performance cementitious materials are discussed. These include chemically bonded ceramics (CBC), a generic term describing ceramic-like materials formed by chemical reactions at ordinary temperatures. Innovations in chemistry, as well as processing, are responsible for the major improvements. MDF and DSP cements are discussed briefly, as are rapid-setting belite-sulfoaluminate and related cements. Applications of certain cements in waste management are also discussed. These include alkali-activated cements, which generate very high early strength, develop a working strength in about 4 hr, have relatively low porosity, and consequently have low permeability. A summary is included of the current status of the materials and their applications, limitations, and potential for further innovations, with a view to applications in the 21st century.
10.14359/4413
SP144-20
M. Collepardi
New superplasticizers are needed to produce concretes with less variability in the slump of the mix at the time of placement, and therefore with less variability in the water-cement ratio. In particular, there are two factors that affect slump at the time of placement: the procedure of superplasticizer addition (immediate or delayed) and time of transportation from the batching plant to the worksite. A new method to produce frost-resistant concrete in structures is needed that does not depend on the numerous factors affecting air volume and, therefore, the performance of air-entrained concrete. The preceding characteristics should allow the concrete to be manufactured under better quality control, which is already in place in the industrial process of other construction materials, such as steel, polymers, and ceramics.
10.14359/4414
SP144-30
N. J. Carino
A brief history of nondestructive testing of hardened concrete over the past 50 years is presented. The underlying principles and inherent limitations of the methods are reviewed, and historical highlights of their development are presented. Test methods are grouped into those that assess in-place strength and those that evaluate nonstrength characteristics, such as flaws and deterioration. Paper concludes with a discussion of the challenges for the 21st century in the area of nondestructive testing.
10.14359/4456
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