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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:
SP91-17
Date:
February 1, 1986
Author(s):
J. Papayianni
Publication:
Symposium Papers
Volume:
91
Abstract:
Lignite Fly Ash (LFA) was used in concrete replacing Portland cement at 0, 30, 40, 50, 60, 70, 80, 9 0 and 100%. Properties investigated in concrete prepared with different percentages of LFA were: 1. Compressive and flexural strengths (7, 28 days 3, 6 months 1, 2, 3, 4 and 8 years). Water to cement plus LFA ratios (W/C+F) 0.55, 0.65, 0.75,0.85, 0.95. Concrete slump 40-50mm, 60-70mm, 80-100mm, lOO-150mm, 150-200mm. A total of 10,000 specimens were tested for compressive strength at various ages during 5 years. 2. Modulus of elasticity according to ASTM C469-65. 3. Bond between steel-concrete according to ASTM C234-71. The test data showed that LFA can replace Portland cement when used as a separate batch material up to 40% in reinforced concrete and up to 70% in plain concrete.
DOI:
10.14359/10079
SP91-18
Shui Cuijuan, Gong Luoshu, and Wang Haimin
Fly ash in China contains low CaO (5%) and is obtained by burning bituminous coal. Thus such a fly ash concrete exhibits low early strength at an optimal dosage of 10-20%. Two methods were adopted to increase the dosage of fly ash (1) introducing calcium directly during burning or (2) as an additive. The effect of dosage of such fly ash on strength, shrinkage, frost resistance, carbonation and steel corrosion of concrete was investigated. Method 1 is effective in improving the activity of fly ash and permits the optimal dosage of fly ash to increase by 30-4O%. Early strength of concrete is also increased. Method 2 is applicable to steam-cured fly ash concrete at a high dosage (5O-60%). X-ray diffraction analysis was used to study the process of reaction between fly ash and cement.
10.14359/10080
SP91-19
R. N. Swamy and H. B. Mahmud
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.
10.14359/10081
SP91-20
K. W. Nasser and A. A. Al-Manaseer
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.
10.14359/10082
SP91-21
A. Heikkinen
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.
10.14359/10083
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