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International Concrete Abstracts Portal

Showing 1-5 of 11 Abstracts search results

Document: 

SP32-09

Date: 

July 1, 1972

Author(s):

C. James Gulde

Publication:

Symposium Papers

Volume:

32

Abstract:

of the materials used in autoclaved block and beick manufacutre contribute to the color, but piin ents contribute the most. Mineral pigments and some others are satisfactory, but all are not effective, and some contain undesirable contaminants. For many colors it is possible to duplicate, in masonry units, any combination of hue, value, and chroma. Versatility in color production and reproduction requires a simple color laboratory and the es-tablishment of a library of color specimens made with the masonry ingredients used by the plant. One patented procedure is based on the introduction of a fluidized color mix onto one face of the machine mold box immediately before each filling of the mold box.

DOI:

10.14359/6605

Document: 

SP32-05

Date: 

July 1, 1972

Author(s):

W. V. Friedlaender and F. V. Camarda

Publication:

Symposium Papers

Volume:

32

Abstract:

The influences of superheated steam on the strengths of autoclave cured cement mortar specimens and asbestos-cement compositions were examined. The test results show that superheated steam, apparently because it acts as a desiccant, generally causes reduced strengths that can be related to functions of the cured weight after autoclaving as well as a factor involvinggthe length and degrees of superheat. If super-heated steam is present during the early stages of the curing cycle it causes greater adverse strength effects.

DOI:

10.14359/6601

Document: 

SP32-10

Date: 

July 1, 1972

Author(s):

Clayton M. Crosier.

Publication:

Symposium Papers

Volume:

32

Abstract:

In connection with extensive laboratory investigations of auto-claved, foamed cellular concretes data have been secured on the effects of variations in the curing on the compressive strength and elasticity. The concretes were made of portland cement. Type I or III, with one of several Kansas pozzolanic materials, or with a fly ash used for comparison. In each of 53 laboratory batches, one curing factor was varied between the 2 or 3 sets of cylinders. This inves tigation covered the effects of each of the four curing variables (in order of extent of coverage): maximum autoclaving pressure, moist storage prior to autoclaving, duration of the maximum pressure, and rate of heating and cooling. The effects of each variable are found to be dependent on the properties of the pozzolan, especially fineness. For the proportions of volcanic ash used and the curing conditions studied, Type III cement was more effective than Type I, but for one fly ash the reverse was true. The analyses are discussed and tentative conclusions are summarized.

DOI:

10.14359/6606

Document: 

SP32-03

Date: 

July 1, 1972

Author(s):

Sergey A. Mironov, Liarisa A. Malinina and Svetlana Cheryachukina

Publication:

Symposium Papers

Volume:

32

Abstract:

The disruptive expansion of concrete which is experienced with either early or rapid application of heat in the autoclave is caused almost entirely by the expansion of the air and water vapor enclosed within the concrete. Deformations in concretre speciments caused by this gaseous expansion during autoclaivng have ben measured. It has been found that if external steamair environment presure is applied properly, these deformations can be prevented. Te method used is to seal the autoclave immediately after introduction specimens, and not vent the air during steaming. The result is that the pressure buildup inside the specimen is actually offset by the couter-pressure of the environment. Higher strenghs were obtained on 10-cm cubes cured in this manner thatn those cured in the usal way. An additional benefit of the method is aht mositure is "locked into" the specimen. Apparently the lack of air migration toward the exteriro helps retain moisture, as indicated by the lower moisture loss meaused when curing with steam-and-using a pressure of 1 atmosphere of air show that pressure reduces moisture loss and increases strength.

DOI:

10.14359/6599

Document: 

SP32-07

Date: 

July 1, 1972

Author(s):

A. V. Satalkin, P. G. Komokhov, and I. P. Kromin

Publication:

Symposium Papers

Volume:

32

Abstract:

Autoclaved concretes using lime-silica binders can be made with strengths of 500-600 kgf/cm2 (7000-8500 psi) or more. Higher strengths are obtained with crushed stone than with sand and gravel aggregate, but concretes without coarse aggregate are more commonly made in the USSR. Although state standard specifications for autoclaved aproducts require that the limes used contain not more than 1 percent MgO, such pure limes are not available throughout the USSR. Concretes have been made in the laboratory using limes with MgO contents as high as 25 percent. Strengths of such concretes are lower, but with additives such as MgC12, CaC12, and NH4Cl these low strength levels can be improved considerably. Concretes made with magnesian limes have withstood more than 200 cycles of freezing and thawing. Reinforcing steel sometimes requires a protective coating to prevent cor-rosion.

DOI:

10.14359/6603

123

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