In today’s market, it is imperative to be knowledgeable and have an edge over the competition. ACI members have it…they are engaged, informed, and stay up to date by taking advantage of benefits that ACI membership provides them.
Read more about membership
Become an ACI Member
Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
American Concrete Institute
38800 Country Club Dr.
Farmington Hills, MI
Chat with Us Online Now
Feedback via Email
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.
Title: Effect of Retempering With Superplasticizer on Properties of Fresh and Hardened concrete mixed at higher ambient temperatures
Author(s): M. A. Samarao, V. Ramakrishnan, and V. M Malhotra
Publication: Special Publication
Appears on pages(s): 273-296
Keywords: compressive strength; flexural strength; fresh concretes; hardened concretes; high temperature; hot weather construction; plasticizers; retempering; water-cement ratio; workability; Materials Research
Abstract:In hot climates, it may be necessary to retemper the concrete to maintain the required workability. The retempering is done by additional dosages of superplasticizer. However, there is a paucity of information on the effects of retempering at higher temperatures. Therefore, an extensive investigation was undertaken to determine the slump loss characteristics and effect of repeated retempering with superplasticizer on the strength and elastic properties of concretes mixed at ambient temperatures ranging from 30 to 60 C (86 to 140 F). A total of 15 concrete mixes with water-to-cement ratios 0.40, 0.50, and 0.60 were made at ambient temperatures of 30, 40, 50, 55, and 60 C (86, 104, 122, 131, and 140 F) to give constant workability. Immediately after mixing and after two retemperings at 30 min intervals, fresh concrete properties (slump, air content, concrete temperature, and unit weight) were determined. Specimens were cast after initial mixing and after two retemperings and tested for hardened concrete properties at 7 and 28 days. The additional water and cement needed to achieve the same workability at higher temperatures is very high for low w/c concrete, whereas there is only a slight increase in the water demand for concretes with w/c 0.50 and 0.60. The increase in the rate of slump loss is not significantly higher at higher temperatures. When retempering with superplasticizer, there are no detrimental effects on fresh as well as hardened concrete properties even under the unfavorable high ambient temperature of 60 C (140 F). The performance characteristics are the same for concretes mixed at higher ambient temperatures and retempered with superplasticizer.
Click here to become an online Journal subscriber