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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 31 Abstracts search results

Document: 

SP68-18

Date: 

January 1, 1981

Author(s):

Traian Ispas and Ion Ionescu

Publication:

Symposium Papers

Volume:

68

Abstract:

The impact of using superplasticizers on total energy consump-tion in the concrete industry is also discussed. Energy savings can result from cement content reduction, heat treatment reduction or elimination, rapid re-use of shutterings, increase of labour productivity, etc.

DOI:

10.14359/6479

Document: 

SP68-19

Date: 

January 1, 1981

Author(s):

Lawrence R. Roberts

Publication:

Symposium Papers

Volume:

68

Abstract:

-v I High range water reducing admixtures (HRWR'S), common y known as superplasticizers, can be used in prestressed or precast concrete to reduce cycle times, cement content, or elevated curing temperatures. With today's high energy costs, the reduction or elimination of elevated curing may provide the greatest payback for the use of such admixtures. In this study, the ability of a naphthalene sulfonate type high range water reducer to decrease the curing energy requirement was investigated using four different cements, one ASTM Type III, two Type I, and one Type I/II. The proportions of the concrete mixtures were fixed at 360 Kg/m3 cement content, while three different temperatures, 22"C, 44"C, and 66"C, were used to cure specimens from each batch. Compressive strengths were determined at 12 or 18 hours, and 28 days. Comparison was made between unadmixtured concrete, that containing a normal water reducing admixture, and that contain-ing the high range water reducer. The ability to reduce curing temperature was shown to depend on the cement type, testing age, and strength requirement to be met. Use of the HRWR permitted reduction of curing temperature for the Type III cement, or substitution of a Type I or I/II cement for the Type III, but not both. At 18 hours age, cement substitution and some tem-perature reduction was possible.

DOI:

10.14359/6480

Document: 

SP68-20

Date: 

January 1, 1981

Author(s):

M. R. Rixom and J. Waddicor

Publication:

Symposium Papers

Volume:

68

Abstract:

The paper describes the assessment and application of the Tattersall two point workability test and a multipoint heat of hydration apparatus in a research project to develop a super-plasticizer based on lignosulphonates. The significance of vari-ables such as ionic type, molecular weight, and degree of sulpho-nation is presented. The application of these variables to produce a suitable lignosulphonate has resulted in a superplasti-cizer which is compared with melamine and naphthalene based pro-ducts. The paper concludes that a superplasticizer based on the new lignosulphonate material is suitable for the production of flowing concrete in terms of dosage requirement, workability extension, price, and compressive strength development.

DOI:

10.14359/6481

Document: 

SP68-30

Date: 

January 1, 1981

Author(s):

N. P. Mailvaganam, R. S. Bhagrath, and K. L. Shaw

Publication:

Symposium Papers

Volume:

68

Abstract:

The sulphate resistance of mortar lng a superplasticizer and made with blends Type 10 cement, fly ash and granulated blast slag are compared with similar mortars conta ventional water reducing admixture. Compari made with mortars made with C.S.A. Type 50 c Changes in porosity, weight, length, dynamictain- elasticity and compressive strength of the exposed to alternate soaking and ium sulphate solutions for 300 days are desc lus of specified-Interrelationship of w/c ratio, alkalinity of the medium and porosity as primary factors in sulphate attack on the cement paste were investigated. The results indicate that mixes containing a 30% replacement of normal Portland cement by fly ash or slag and a superplasticizer are comparable to mixes made from sulphate resisting cement in their capacity to resist sulphate attack. The degree of attack noted in the superplasticized mixes was significantly reduced in com-parison with mortars where a conventional water reducing admixture was used.

DOI:

10.14359/6491

Document: 

SP68-15

Date: 

January 1, 1981

Author(s):

M. Kobayashi, E. Nakakuro, K. Kodama, and S. Negami

Publication:

Symposium Papers

Volume:

68

Abstract:

First, the paper shows the results of microscope analyses of concretes using three high-range water-reducing admixtures of different chemical compositions and having different water-cement ratios and air contents in order to determine the air-void systems of concretes containing high-range water-reducing admixtures, and also discusses the selection of the air-entraining admixture to be jointly used. Secondly, the paper deals with the relation between frost resistance and spacing factor based on the results of rapid freezing and thawing tests on concretes made with high-range water-reducing admixtures and further gives air contents or spac-ing factors required to give concrete adequate resistance to severe frost action. The results of tests on the effects of different kinds of high-range water-reducing admixtures on surface tension, foaming, and stability of air bubbles are given.

DOI:

10.14359/6476

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