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International Concrete Abstracts Portal

Showing 1-5 of 18 Abstracts search results

Document: 

SP223-01

Date: 

October 1, 2004

Author(s):

Bryant Mather

Publication:

Symposium Papers

Volume:

223

Abstract:

Concrete is international, but made locally; has infinite variability, but can be made very uniform; and can be made to last as long as you want it to. Therefore, what is needed to more fully realize its potential as a construction material is to understand what we want it to do, learn how to make it so it will do so, use available methods to restrict undesired variability, consider the ethical and environmental aspects of its use, and help the people who are making it to do it better.

DOI:

10.14359/13493


Document: 

SP223-09

Date: 

October 1, 2004

Author(s):

Bryant Mather

Publication:

Symposium Papers

Volume:

223

Abstract:

The phenomena related to the formation of hydrated sulfates in concrete, or in aggregates, cement pastes, or mortars, have been investigated for many years for a variety of purposes. The cyclic immersion of aggregate particles in solutions of sodium or magnesium sulfate, followed by drying, is the basis of one of the oldest procedures employed to develop data purported to relate to aggregate "soundness." The storage of mortar specimens in sulfate solutions is the basis of many tests for sulfate resistance of cements. Sulfate-resistance testing procedures in which the mortar is mixed with added sulfate and the specimens are stored in water are in widespread use. These latter procedures are similar to procedures employed in studies of expansive cements.

DOI:

10.14359/13501


Document: 

SP223-17

Date: 

October 1, 2004

Author(s):

Bryant Mather

Publication:

Symposium Papers

Volume:

223

Abstract:

In a letter in the September 2000 issue of Concrete International, D. Srinivasan asked, "Will there be a self-curing concrete?" My answer to this is strongly affirmative for three reasons. First, most of the concrete that is produced and placed each year all over the world already does self-cure. Some of it wasn’t intended to have anything done to its exterior surface. But finishing did in fact take place, and yet the concrete’s ability to serve its intended purpose had not been significantly reduced.

DOI:

10.14359/13509


Document: 

SP223-05

Date: 

October 1, 2004

Author(s):

Bryant Mather

Publication:

Symposium Papers

Volume:

223

Abstract:

Concrete will be immune to the effects of freezing and thawing if (1) it is not in an environment where freezing and thawing take place so as to cause freezable water in the concrete to freeze, (2) when freezing takes place there are no pores in the concrete large enough to hold freezable water (i.e., no capillary cavities), (3) during freezing of freezable water, the pores containing freezable water are never more than 91 percent filled, i.e., not critically saturated, (4) during freezing of freezable water the pores containing freezable water are more than 91 percent full, the paste has an air-void system with an air bubble located not more than 0.2 mm (0.008 in.) from anywhere (L = 0.2 mm), sound aggregate, and moderate maturity. Sound aggregate is aggregate that does not contain significant amounts of accessible capillary pore space that is likely to be critically saturated when freezing occurs. The way to establish that such is the case, is to subject properly air-entrained, properly mature concrete, made with the aggregate in question, to an appropriate laboratory freezing-and-thawing test such as ASTM C 666 Procedure A. Moderate maturity means that the originally mixing water-filled space has been reduced by cement hydration so that the remaining capillary porosity that can hold freezable water is a small enough fractional volume of the paste so that the expansion of the water on freezing can be accommodated by the air-void system. Such maturity was shown by Klieger in 1956 to have been attained when the compressive strength reaches about 4,000 psi.

DOI:

10.14359/13497


Document: 

SP223-16

Date: 

October 1, 2004

Author(s):

Bryant Mather

Publication:

Symposium Papers

Volume:

223

Abstract:

Douglas Southall Freeman’s authoritative biography of Robert E. Lee has a chapter on the building of Fort Carroll in the middle of Baltimore Harbor in 1849-1852. In the spring of that year, Lee established that there was a stable hard surface 45 ft below low water and began to work on the construction. These preliminary activities, as recounted by Freeman, included the following: "He experimented in the laying of concrete under water with a tremie." Lee continued with the work until August 1852 when he was sent to be Commandant at West Point. By then some concrete had been placed in Fort Carroll. Lee received information from General Totten on 22 June 1849 on placing concrete with a tremie. Lee replied on 25 June, "I shall make experiments to test the tremie preparatory to laying foundations." These experiments are among the earliest bits of concrete research done in the USA.

DOI:

10.14359/13508


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