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

Mix Proportions and Strength Characteristics of Concrete Containing 50 Percent Low-Calcium Fly Ash

Document:

SP91-19

Date:

February 1, 1986

Author(s):

R. N. Swamy and H. B. Mahmud

Publication:

Symposium Papers

Volume:

Abstract:

Data on the mix design, strength and elasticity properties of concrete containing 50% low calcium fly ash replacement and a superplasticizer for 28 day strengths of 20 to 60 MPa are presented. It is shown that for concretes with low water-cement ratios of 0.32 to 0.42, high early strength of 12 to 20 Mpa in one day and 28 day strengths of 45 to 60 MPa can be produced with slumps in excess of 150mm. Under wet curing such concretes can give strength increases of 50 to 100% from 28 days to one year compared to increases of 18 to 25% for all OPC concretes. Even under the worst curing conditions, fly ash concretes showed a slow but steady strength gain and maintained their target strengths at one year whereas all OPC concretes under similar conditions showed strengths of 25 to 35% below the target strength. Air drying always produced greater losses in strength and elasticity in all OPC concretes than in fly ash concretes. The latter were able to develop flexural strengths of 3.5 to 6.0 MPa and tensile splitting strengths of 2.0 to 4.5 MPa at one year under these conditions. The practical and technical benefits of incorporating high fly ash contents are emphasized.

DOI:

10.14359/10081

Shrinkage and Creep of Concrete Containing 50 Percent Lignite Fly Ash at Different Stress-Strength Ratios

Document:

SP91-20

Date:

February 1, 1986

Author(s):

K. W. Nasser and A. A. Al-Manaseer

Publication:

Symposium Papers

Volume:

Abstract:

A study was conducted to find the shrinkage and creep of sealed and unsealed concrete made with Type I cement and containing 50% Saskatchewan fly ash. The tests were carried out at different stress/strength ratios and creep was measured at those ratios of: 10, 20, 30, 40, 50, and 60% and for a maximum period of 112 days. All the tests were carried out at room temperature of 70°F (21.4OC). Experimental results showed that creep of concrete made with 50% fly ash was a linear function of stress/strength ratio. The shrinkage of this concrete was about 11% higher than that of plain concrete, while its creep was lower by about 13% for the unsealed specimens and 39% for the sealed ones. In addition, the ratio of creep values of unsealed/sealed concrete was about 2.44 for plain concrete and 3.67 for concrete with 50% fly ash.

DOI:

10.14359/10082

Use of Peat Ash in Concrete

Document:

SP91-21

Date:

February 1, 1986

Author(s):

A. Heikkinen

Publication:

Symposium Papers

Volume:

Abstract:

Peat ash is suitable for use as a constituent of concrete. The quality and quantity of admixtures and ash used in concrete have a strong influence on the development of compressive strength.

DOI:

10.14359/10083

Long-Term Durability of Blended Cement Concretes in Structures

Document:

SP91-22

Date:

February 1, 1986

Author(s):

H. Roper, G. Kirkby, and D. Baweja

Publication:

Symposium Papers

Volume:

Abstract:

Although abundant data are available on early-age properties of blended cement concretes, relatively little information has been published on the long-term durability of blended cement concretes in service. The paper is a summary of an investigation of over two hundred structures in Australia. Some of these have service lives in excess of twenty years. Cored materials from some of the structures are described, and petrological and mineralogical examination allow conclusions on the efficacy hydration processes under field curing to be made. Porosity and permeability is discussed. Carbonation and corrosion effects on long-term durability are considered by the examination of data obtained from in situ concretes. The interactions between cement content and water: cement ratio on carbonation rate is discussed, and data from concretes both from in service and laboratory mixes are considered. Cracking is the predominant defect observed on most of the examined concrete surfaces and the role of pozzolans on elastic deformations, creep and shrinkage of concrete in structures is discussed. Data suggest that, for those structures studied, the long-term durability of blended cement concretes is at least the equal of ordinary portland cement concretes under service conditions.

DOI:

10.14359/10084

Effect of Fly Ash on the Durability of Air-Entrained Concrete

Document:

SP91-23

Date:

February 1, 1986

Author(s):

S. H. Gebler and P. Klieger

Publication:

Symposium Papers

Volume:

Abstract:

Concretes containing fly ash were evaluated to establish the effect of the fly ash on freeze-thaw resistance, resistance to deicer scaling, and chloride ion penetration. The effects of low temperature curing and moisture availability during curing were also evaluated. These tests indicated that the freeze-thaw resistance of air-entrained concrete was reduced by the use of certain fly ashes when cured at low temperature. For other conditions there was no significant influence of fly ash . Deicer scaling resistance tests showed that air-entrained concrete without fly ash generally performed somewhat better than concrete with fly ash, regardless of the type of curing provided. Air-entrained concretes made with some fly ashes were as resistant to chloride ion penetration as air-entrained concrete without fly ash. The class of fly ash did not significantly influence the degree of chloride ion penetration.

DOI:

10.14359/10085

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