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Home > Publications > 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 31 Abstracts search results
Document:
SP68-23
Date:
January 1, 1981
Author(s):
James S. Hampton
Publication:
Symposium Papers
Volume:
68
Abstract:
Normally in hot weather, it is difficult to maintain the workability of concrete containing high-range water-reducing admixtures (H-R W-RA) as the concrete temperatures approach 85 - 90°F(29 to 32oC). The loss of fluidity and workability often occurs within 30 min. after the introduction of the adrnix-ture making placement and pumping very difficult if there are delays. This paper discusses how certain modified H-R W-RA may be used to provide fluidized concrete with prolonged work-ability.
DOI:
10.14359/6484
SP68-22
V. S. Ramachandran
a few as Ca-acid, concre Of the slump in mor Superpla hours. The e lignosulfonat Na-heptonate te containing se admixtures loss; the inf tars was also sticized concrete 1 ffect of different , sucrose, Na-glut and Na-boroheptonat sulfonated melamin Na-gluconate prov luence on setting t examined. oses its workability within amounts of admixtures, such onate, citric acid, salicylic, on the slump loss of formaldehyde is reported. to be the best retarder of times and strengthdevelopment
10.14359/6483
SP68-21
V. G. Gokhale and R. Paranjpe
Today, the developing countries have sufficient techni-cal manpower and basic research facilities to develop indigenous know-how for most chemicals. As far as superplasticizers are concerned, Gas-layer Chromatographic equipment, Infra-red/Ultra-violet spectrometers and a well equipped analytical chemical laboratory are adequate to develop know-how indigenously. The paper describes such development work which has been successfully done in India. Such production of superplasticizers is essential to developing countries where cement shortages and poor quality cement seriously hamper construction work of large and essential projects.
10.14359/6482
SP68-20
M. R. Rixom and J. Waddicor
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.
10.14359/6481
SP68-19
Lawrence R. Roberts
-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.
10.14359/6480
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