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International Concrete Abstracts Portal

Showing 1-5 of 112 Abstracts search results

Document: 

SP100-96

Date: 

April 1, 1987

Author(s):

Thomas L. Hugenberg

Publication:

Symposium Papers

Volume:

100

Abstract:

Expansion of the concrete at Center Hill Dam during its 38-year service life resulted in binding of the spillway gates and closing of the expansion joints in the bridge spans in 1983. An extensive laboratory and field investigation identified an alkali-carbonate rock reaction as the cause of expansion. Shortening of the spillway gates and bridge spans in 1985 remedied the operational deficiencies.

DOI:

10.14359/3330


Document: 

SP100-03

Date: 

April 1, 1987

Author(s):

Adam Neville

Publication:

Symposium Papers

Volume:

100

Abstract:

Draws attention to some early papers by both the Mathers of particular and lasting significance. Three factors relevant to so many current problems with durability of concrete are reviewed: first, inadequate criteria for acceptance of concrete, strength alone being relied upon in the past; second, changes in cement properties over the years, which allowed the use of leaner mixes for a given specified strength; and third, the corrosion of steel in the concretes used nowadays, particularly severe in hot climates. Finally, recommendations are made for more attention to the composition of the mix and for inspection and maintenance of concrete structures.

DOI:

10.14359/3525


Document: 

SP100-47

Date: 

April 1, 1987

Author(s):

Peggy M. Carrasquillo

Publication:

Symposium Papers

Volume:

100

Abstract:

The effect of fly ash content on the air entrainment, freeze-thaw durability, abrasion resistance, strength gain, shrinkage, and creep of concrete was studied. Two different fly ashes were used to replace 0, 20, and 35 percent of a portland cement by weight. A blended cement, containing 20 percent fly ash by weight, was also tested. Three different air entraining admixtures were used. It was found that the use of fly ash in concrete could reduce the effectiveness of air-entraining admixtures depending on properties of the fly ash, such as loss on ignition (LOI). However, concrete containing fly ash exhibited freeze-thaw resistance equal to or better than that of similar concrete containing portland cement only, provided both had similar entrained air contents. Similarly, concrete containing fly ash showed equal or better resistance to abrasion when compared to concrete of equal strength containing no fly ash. The strength gain characteristics of concrete containing fly ash are different from those of concrete containing no fly ash. The creep of concrete containing fly ash was found to be less than or equal to that of portland cement concrete when subjected to equal sustained loads, even though the 28 day compressive strength of the concrete containing fly ash was lower than that of concrete containing no fly ash. The shrinkage of concrete containing fly ash is highly dependent on the curing given to the concrete and on environmental conditions, such as temperature and relative humidity. Not only is the shrinkage of concrete containing fly ash affected by the previously mentioned conditions differently than that of concrete containing no fly ash, but concrete containing Class C fly ash is affected differently than concrete containing Class F fly ash.

DOI:

10.14359/1962


Document: 

SP100-58

Date: 

April 1, 1987

Author(s):

M. Sugiyama, K. Tanaka, M. Sakuta, and T. Urano

Publication:

Symposium Papers

Volume:

100

Abstract:

The authors have carried out a series of studies on admixtures for reducing drying shrinkage of concrete. Regarding these admixtures, extremely interesting properties were found in a glycol ether derivative that is a water-insoluble, non-air-entraining surface active agent. The following points were revealed: 1) The water-insoluble glycol ether holds down air content of the concrete to less than about 1 percent. 2) Drying shrinkage of concrete is remarkably reduced when this glycol ether derivative is added to concrete. 3) Durability against freezing and thawing of concrete containing this glycol ether derivative is improved extremely by allowing the concrete to dry slightly prior to starting the freezing and thawing test. 4) Although the total volume of air is small, the number of air bubbles present is large because the diameters of the air bubbles are very small.

DOI:

10.14359/2058


Document: 

SP100-35

Date: 

April 1, 1987

Author(s):

Stella L. Marusin

Publication:

Symposium Papers

Volume:

100

Abstract:

Research since 1979 on sealers, coatings, and concrete containing admixtures is summarized. A test procedure developed during a National Cooperative Highway Research Program project, "Concrete Sealers for Protection of Bridge Structures," was used. This test method uses 10 cm cube specimens, and water absorption and chloride ion penetration is determined after 21 days of exposure to 15 percent NaCl solution. The study focuses on the minimization of the ingress of chloride-laden water into concrete, the influence of water-cement ratio, the relationship between water absorption and chloride ion content in concrete, and the comparison of the chloride distribution profiles through the conventional portland cement concrete and concrete containing various admixtures (superplasticizers, polymer emulsions, condensed silica fume).

DOI:

10.14359/1906


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