International Concrete Abstracts Portal

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: 

SP91-74

Date: 

February 1, 1986

Author(s):

John P. H. Frearson

Publication:

Symposium Papers

Volume:

91

Abstract:

Laboratory test programmes have been carried out to assess the sulphate resistance of various Portland and Portland blast-furnace slag cements and of Portland cements blended with ground granulated blast-furnace slag ('slag'). Slag contents of between 30% and 80% were used. The test method was based upon the German 'Flat Prism' test. Tests were carried out on mortars containing ground slag from two sources, also pulverjsed fuel-ash (pfa - 'fly ash'), and with Portland blast-furnace cements. Control specimens contained either ordinary or sulphate resisting Portland cements. Prisms were tested at water-cement ratios (w/c) ranging from 0.45 to 0.60, using constant cement contents mortars. Supplementary tests used w/c ranging from 0.40 to 0.60 and constant water content mortars. Results are now available for mortars which have been immersed in sodium sulphate solution for periods of up to 3 years. The results confirm the inferior resistance to sulphate attack of ordinary Portland cements and of blends of both ordinary and sulphate resisting Portland cement containing lower slag replacement levels. Sulphate resistance increased as the slag content increased, and the 70% slag content mortars were found to have a superior resistance to those containing sulphate resisting Portland cements alone. The influence of slag content on sulphate resistance was found to be more significant than that of the w/c in the range examined.

DOI:

10.14359/10133


Document: 

SP91-75

Date: 

February 1, 1986

Author(s):

E. Douglas, P. R. Mainwaring, and R. T. Hemmings

Publication:

Symposium Papers

Volume:

91

Abstract:

Copper, nickel and lead slags of Canadian origin have been studied to evaluate the feasibility of their use as partial portland cement replacement in concrete and mine backfill. Pozzolanic activity of the slags was tested in mortars and the corresponding Ca(OH)2 and non-evaporable water contents at the same age were obtained by thermogravimetric analysis. The relationship between pozzolanic activity and glass content, measured by SEM and image analyzer, was assessed as well. It is concluded that non-ferrous slags could be used as partial Portland cement replacement in concrete and mine backfill if Portland cement and transportation costs justify it.

DOI:

10.14359/10134


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


Document: 

SP91-31

Date: 

February 1, 1986

Author(s):

Oscar E. Manz

Publication:

Symposium Papers

Volume:

91

Abstract:

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.

DOI:

10.14359/1779


Document: 

SP91-32

Date: 

February 1, 1986

Author(s):

P. F. Walsh

Publication:

Symposium Papers

Volume:

91

Abstract:

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.

DOI:

10.14359/1780


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