Title: Enhancing Durability of Heat Cured Concrete with Novel Superplasticizers

Author(s): R. Khurana and A. G. Schmid

Publication: Symposium Paper

Volume: 192

Issue:

Appears on pages(s): 339-352

Keywords: curing; durability; ettringite; microcracking; superplasticizers

DOI: 10.14359/5758

Date: 4/1/2000

Abstract:
Heat curing is very commonly used in the production of precast concrete elements to allow for a rapid demoulding and frequent reuse of the casting beds. Curing temperatures up to 70 degrees C are often used to obtain high early strengths from 30 to 55 MPa. at ages ranging from 6 to 16 hours. Heat curing may influence negatively the durability of the precast concrete elements in several ways such as strength loss, formation of micro cracks which are preferential paths for ingress of aggressive agents and delayed ettringite formation and subsequent cracking. This paper examines the use of novel polycarboxylic either base superplasticizers which allow for a high water reduction (up to 40%) in the concrete mix, in order to obtain high early strengths at curing temperatures considerably lower than those utilized at present and in some cases, eliminating the heat curing . Several case histories of applications in Europe are presented where the benefits of the low water-cement ratio of the concrete mixes, combined with a very high workability, contribute to enhance the durability of precast concrete structures.