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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 78 Abstracts search results
Document:
SP91-30
Date:
February 1, 1986
Author(s):
P. K. Mehta
Publication:
Symposium Papers
Volume:
91
Abstract:
Concern is growing that prescriptive and separate standards are an obstacle to widely using such by-product mineral admixtures as fly ash, granulated slag, and condensed silica fume. Since natural as well as by-product pozzolanic and cementitious admixtures offer similar technical benefits when used in concrete, it is desirable to develop a single performance-oriented standard. With this objective, the principal chemical and physical requirements of a few selected standards are reviewed, with a focus on fly ash and its relevance to current materials. A rational approach is suggested and specific recommendations made toward developing a performance standard to cover all mineral admixtures.
DOI:
10.14359/1778
SP91-31
Oscar E. Manz
Many of the current standards for fly ash to be used in portland cement suffer from prescriptive requirements not necessarily related to the material's performance in concrete. The development of performance specifications is being encouraged, and classifying fly ash by reference to type of coal is being questioned. To use fly ash as a mineral admixture, the potential strength contribution to a reference mortar seems to be the most important consideration. To overcome the inconsistency with cement in the ASTM C 311 pozzolanic activity index, many countries have revised the test by incorporating fixed fly ash/cement ratio by weight, fixed water/cement + ash ratio, and accelerated curing at various temperatures for up to 7, rather than 28, days. Various studies to improve pozzolanic test methods are summarized, and recommendations made to simplify present fly ash standards, and to change their orientation from prescriptive to performance.
10.14359/1779
SP91-32
P. F. Walsh
In drafting the durability section of the Australian concrete code, the committee faced both an urgent problem and a lack of precise data. This paper outlines the concepts in the draft code with a particular emphasis on the protection of reinforcement and the influence of fly ash on durability. Based on a qualitative understanding of the fundamental parameters, some engineering decisions and classifications are made. Where ample curing or self-curing is available, fly ash is a desirable component of durable reinforced concrete. For building exteriors where minimal curing is provided, achieving quality concrete cover is difficult. In this respect, concrete containing fly ash may be more affected than plain concrete.
10.14359/1780
SP91-56
F. F. Radjy, T. Bogen, E. J. Sellevold, and K. E. Loeland
Extensive technical work has established that high-performance concrete and cementitious materials can be proportioned practically and economically by using condensed silica fume additives. These hybrid chemical/mineral admixtures can be used for applications ranging from bridge overlays, concrete roof tiles, and fiber reinforced cements to structural uses, both on land and offshore. First significant applications began some ten years ago in Norway, with cement replacement as the main benefit. While cement replacement still continues as the main end use in the Scandinavian markets, performance enhancement of cementitious and concrete applications is the dominant attraction for users outside of Scandinavia. After a brief consideration of the history, a range of durability and high-strength applications are reviewed. It is shown that this range of varied applications is generally driven by particular features of performance enhancement.
10.14359/1781
SP91-76
F. J. Hogan and J. H. Rose
In the United States, blast furnace slag was first used as a cementitious material in 1896. Since that time its use has followed a course of limited and sporadic success. Recently, however, world-wide attention has been drawn to the technical advantages of ground granulated blast furnace slag used as a separate cement to be added at the concrete mixer. Recognizing its potential, the ASTM Subcommittee E38.06.02 developed a specification to cover three grades of ground granulated slag. This paper discusses the development of the specification and presents round-robin test data leading to the adoption of a test method for evaluating the hydraulic characteristics of slags. Adopted in 1982 as ASTM C 989, the specification has played an important role in market growth which is approaching 1.0 million tons annually. Test results from another ASTM cooperative test program demonstrating the usefulness of a rapid (24 hr) hydraulicity test method are also given.
10.14359/1782
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