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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 112 Abstracts search results

Document: 

SP100-18

Date: 

April 1, 1987

Author(s):

Paul Poitevin

Publication:

Symposium Papers

Volume:

100

Abstract:

In the last century, lime concrete, portland cement concrete began to be used for breakwaters, quay walls, and lighthouse towers. Now both for inshore and offshore structures, concrete, reinforced or prestressed, is widely accepted as a most economical material. Its durability is no more questioned as the resistance of hydraulic binders to the chemical attack of seawater has been the object of extensive research and long duration tests. In France, public authorities and cement manufacturers, in close collaboration, have established criteria to evaluate cements for works in marine environment, and each year a list of available cements complying with these criteria is published. The results of the research conducted in the maritime laboratories of the Ministry of Public Works, and in the exposure stations of CEBTP and CNEXO are reviewed. Composite Portland cements, now 70 percent of the French production, call for new research if they are to be used at sea. An accelerated test is now proposed to verify their suitability for marine structures. 105-387

DOI:

10.14359/1824

Document: 

SP100-21

Date: 

April 1, 1987

Author(s):

R. Munoz Martialay

Publication:

Symposium Papers

Volume:

100

Abstract:

The results obtained on the evolution of permeability to air of six slabs for a period of 20 years are described. Measurements were taken at four pressure levels: 0.40, 0.95, 1.35, and 1.90 kp/cmý. The concrete plates of 1 x 1 x 0.20 m were placed in a test chamber. The results from permeability have a qualitative value, as boundary effects are unknown. In the bibliography, the publication includes quantitative results of eight concretes of different dosage. Differences obtained among the slabs, even having the same dosage and being similarly conserved, are pointed out. Twenty years after the concrete was made and in normal preservation conditions of a test chamber, a tendency to stabilization of permeability values is observed, especially in the lower pressure, 0.40 kp/cmý.

DOI:

10.14359/1846

Document: 

SP100-23

Date: 

April 1, 1987

Author(s):

Gary L. Vondran

Publication:

Symposium Papers

Volume:

100

Abstract:

Materials Research

DOI:

10.14359/1857

Document: 

SP100-63

Date: 

April 1, 1987

Author(s):

V. M. Malhotra, G. G. Carette, and T. W. Bremner

Publication:

Symposium Papers

Volume:

100

Abstract:

Evaluation in marine environment of normal and lightweight concretes incorporating supplementary cementing materials is discussed. A series of 138 concrete prisms, 305 x 305 x 915 mm in size, were cast over a five-year period starting in 1978, for long-term exposure at Treat Island, Maine. The prisms were positioned at mid-tide level on a rack at the entrance to the Bay of Fundy, and this represents what is perhaps the most severe marine exposure conditions for concrete. The test specimens are exposed to repeated cycles of wetting and drying and to an average of about 100 cycles of freezing and thawing per year. The test specimens are monitored at yearly intervals: the specimens are photographed and rated on a visual basis. Ultrasonic pulse velocity is also determined. After up to 8 years of exposure, both normal-weight and lightweight air-entrained concretes show no degradation of the mass of the concrete; however, some of the specimens show significant surface deterioration. The amount of deterioration generally increases with an increasing water-to-cementitious materials ratio, and increasing replacement of cement with slag and fly ash. It appears that surface deterioration can be avoided if the cement content is kept to at least a certain minimum level. The tests confirm that over long exposure duration, non-air-entrained concrete is not durable in this environment.

DOI:

10.14359/2094

Document: 

SP100-92

Date: 

April 1, 1987

Author(s):

Mitsunori Kawamura, Kunio Takemoto, and Shigemasa Hasaba

Publication:

Symposium Papers

Volume:

100

Abstract:

To use silica fume as a pozzolanic material for inhibiting alkali-silica expansion, the effects of various silica fumes on expansion of mortars containing Beltane opal were investigated. Different silica fumes were found to vary widely in their effect on the expansion of mortars. The properties of silica fume affecting alkali-silica expansion were explored. Pozzolanic activity of silica fumes was evaluated by measuring the amounts of calcium hydroxide consumed by pozzolanic reaction in silica fume-bearing cement pastes. The amounts of calcium hydroxide in portland cement-silica fume mixtures were determined by DSC-TG analysis. Pore solutions obtained from mortars containing three different silica fumes were also analyzed. The silica fume with the highest pozzolanic activity was the most effective in reducing alkali-silica expansion of mortars. However, it was found that reduction in expansion by the addition of silica fume was not necessarily in line with the amount of calcium hydroxide consumed as a whole. Although the concentrations of alkalis and OH- ions in the pore solutions in mortars were reduced to the same level by the addition of three different silica fumes, the reductions in expansions of the three silica fume-bearing mortars were greatly different from one another.

DOI:

10.14359/2107

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