International Concrete Abstracts Portal

Home > Publications > International Concrete Abstracts Portal

International Concrete Abstracts Portal

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 23 Abstracts search results

Document: 

SP131-01

Date: 

March 1, 1992

Author(s):

V. Ukraincik and D. Bjegovic

Publication:

Symposium Papers

Volume:

131

Abstract:

The greatest threat to the durability of reinforced concrete structures is the reinforcement corrosion. The paper presents the importance of the concrete protective cover and the conditions causing the reinforcement corrosion under the action of chlorides and carbonic acid. Processes of absorption, diffusion and flow, i.e. of transport of media through concrete depend on the pore system and the amount of water in the pores.Physical laws describing the penetration of aggressive agents into concre-te can serve as a basis for engineering calculations of reinforcement durability in the concrete as well as for the designing of the concrete cover. Physical laws and corresponding material parametars are briefly reviewed in the paper. For engineering purposes, in calculating the durability, four typical tasks can be solved. The processes of degradation depend on the pore system in the concrete structure, and the paper indicates some possible technological measures of structure modifications.

DOI:

10.14359/10025

Document: 

SP131-07

Date: 

March 1, 1992

Author(s):

Sidney Diamond and Michael Penko

Publication:

Symposium Papers

Volume:

131

Abstract:

Among the important stages of the overall SR process as it occurs in concrete is the conversion of alkali sulfate dissolved from the cement to alkali hydroxide. The results of laboratory studies are presented to provide an understanding of this process and its effects. This conversion process depends on continued formation of ettringite and does not take place until the cement gypsum is exhausted. Provision of a large excess of gypsum or interference with early ettringite production by high-temperature exposure may postpone or prevent it, thus reducing the OH - ion concentration and the possibility of ASR reaction.

DOI:

10.14359/1206

Document: 

SP131-08

Date: 

March 1, 1992

Author(s):

Bryant Mather

Publication:

Symposium Papers

Volume:

131

Abstract:

Most authoritative works that discuss the issue of whether or not calcium chloride should be used as an accelerating admixture in concrete made with Type V sulfate-resisting cement warn against its use. The origin of this warning is reviewed, and the conclusion is reached that it is probably not harmful to obtaining the desired level of sulfate resistance (for which the use of Type V cement was specified) to use calcium chloride in normally acceptable amounts as an accelerating admixture in such concrete to mitigate the effects of cold weather.

DOI:

10.14359/1207

Document: 

SP131-09

Date: 

March 1, 1992

Author(s):

Ephraim Senbetta and Mark A. Bury

Publication:

Symposium Papers

Volume:

131

Abstract:

Recent developments in admixture technology have made possible significantly greater control of the hydration of cement. This control has enabled concrete producers and users to stop cement hydration at any time between the initial mixing of the concrete and just prior to initial set, and has enabled restarting it at any time, allowing the concrete to set normally. This means that one can make concrete today and use it tomorrow, the next day, or some other time in the near future. When one interferes with cement hydration in the manner just mentioned, it is natural to wonder how the properties of the concrete are affected. A large number of evaluations have shown that the properties of concrete treated with a chemical system having such an impact on cement hydration are equal to or better than those of plain concrete. There have been a few publications to this effect, and they have focused on strength and some other basic material properties. Paper deals with the effect of cement hydration control on the durability of concrete. To this end, both basic material properties of concrete related to durability and the actual performance (durability) test results are provided. The data in this paper clearly indicate that none of the durability-related parameters examined were adversely affected by the use of the hydration control chemical system. On the contrary, compressive strength, corrosion of steel, and the susceptibility of concrete to cracking parameters were improved.

DOI:

10.14359/1208

Document: 

SP131-10

Date: 

March 1, 1992

Author(s):

Della M. Roy

Publication:

Symposium Papers

Volume:

131

Abstract:

The hydration and factors relating to the durability of hardened cement paste and concrete have been investigated. Both chemical and physical factors involved in the paste and concrete microstructure are governing factors in prediction of performance. This paper addresses the effects of cementitious materials modified by the presence of granulated blast furnace slag, fly ash, or silica fume. Special alkali-activated cements are also discussed. Initial structure developed in the fresh state is transmitted to the final structure, including the paste pore structure, and is important in resisting forces of degradation. Considerable advances have been made in understanding the mechanisms of degradation, such as shrinkage, freezing, and thawing, carbonation, intrusion of undesirable chemicals, or leaching of species to the environment.

DOI:

10.14359/1209

12345

Results Per Page