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International Concrete Abstracts Portal

Showing 1-5 of 7 Abstracts search results

Document: 

SP77-06

Date: 

October 1, 1982

Author(s):

Paul Wencil Brown

Publication:

Symposium Papers

Volume:

77

Abstract:

It was initially established that the maintenance of the pH of a sulfate solution, in which mortar specimens were immersed, at a constant and predetermined value through controlled sulfuric acid additions.ensured that the sulfate ion concentration in solution remained invariant with time. The rates of sulfate attack of mortar specimens exposed under typical immersion and environmentally controlled conditions were then compared. It was observed that environmental control significantly increased the rate of sulfate attack as measured either by strength loss or linear expansion. However, the strength changes and the expansions observed occurred in a manner consistent with the severity of the test conditions imposed.

DOI:

10.14359/6422

Document: 

SP77-05

Date: 

October 1, 1982

Author(s):

Thomas J. Reading

Publication:

Symposium Papers

Volume:

77

Abstract:

Evidence is presented to show that sodium sulfate attack on concrete has physical, as well as chemical aspects. This has been shown in the laboratory and in studies of field structures, Including ft. Peck Dam. Inspection, coring, and testing of the Ft. Peck concrete after 40 years of severe sulfate exposure are described. Sulfate attack was noted in a fen areas, but the overall condition of the concrete is surprisingly good.

DOI:

10.14359/6421

Document: 

SP77-04

Date: 

October 1, 1982

Author(s):

Katharine Mather

Publication:

Symposium Papers

Volume:

77

Abstract:

Two studies relating to sulfate resistance are being carried out under the direction of the author. One of these, a cooperative program in ASTM Committee C-l, is to develop a performance test for sulfate resistance of cements that treats blended cements fairly. The other, a Corps of Engineers Civil Works Research Unit, is to evaluate substitutes for sulfate resisting cements. In the latter study, data have been developed showing that some pozzolans are very effective in preventing sul-fate attack expansion of mortars made with non-sulfate resisting cements. The most effective pozzolans appear to be those of high fineness, high silica content, and a high degree of amorphousness of the silica, characteristics that were shown previously to be possessed by pozzolans that are effective in reducing expansion due to the alkali-silica reaction. Other pozzolans, notably some fly ashes, were found to increase the rate of deterioration of mortar bars made with non-sulfate-resisting cements exposed to sulfate solution when used as cement replacements at the30 percent level. These were fly ashes derived from combustion of lignite.

DOI:

10.14359/6420

Document: 

SP77-03

Date: 

October 1, 1982

Author(s):

Edwin R. Dunstan, Jr.

Publication:

Symposium Papers

Volume:

77

Abstract:

Webster defines odyssey in ectual wandering or quest. as an extended, adventurous, Whether or not it be possible, it has been the concrete engineer's quest to have an ideal, all-encompassing specification (spec) for concrete exposed to sulfate environments. This paper is a concept, or scenario, which attempts to provide an all-encompassing specification. A factor for sulfate resistance has been developed which incorporates several factors. These include the chemistry of the cement (C3A and C3AF contents), water to cement ratio or water to cement plus blended material ratio, the percentage of pozzolan or blended material used, and the severity of the sulfates in ground water or soil. This factor, FSR, is correlated to service life. It is predicted that a FSR of 40 as calculated herein will produce a concrete having a service life of 50 years. Constructive criticism of this concept is invited to develop this concept into an all-encompassing specification or prove that such a specification is still only an intellectual quest or odyssey.

DOI:

10.14359/6419

Document: 

SP77-02

Date: 

October 1, 1982

Author(s):

David Stark

Publication:

Symposium Papers

Volume:

77

Abstract:

Eleven year performance data are presented for concrete beams stored in sulfate bearing soil in Sacramento, California. Concrete variables include ASTM cement type, cement factor, air entrainment, pozzolanic replacements for cement, portland blast-furnace slag cement, and steam curing. Results reaffirm the importance of cement type, that is, the tricalcium aluminate content of the cement and, more significantly, cement factor with attendant change in water-cement ratio on resistance to sulfate attack. In this study, the use of 40% replacements of cement by high alumina granulated blast-furnace slags had a generally detrimental effect on concrete durability. Twenty percent fly ash replacements were beneficial in the leaner mixes but generally of little or no value in the richer mixes. Forty percent fly ash replacements were generally detrimental to sulfate resistance, particularly where Types II and V cement were used in richer mixes. Calcined Monterey shale showed similar trends but with a greater dropoff in durability in the richer mixes. Air entrainment and steam curing were beneficial to varying degrees.

DOI:

10.14359/6418

12

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