Title: Air-void stability, Part III: Field tests of superplasticized concretes

Author(s): Francois Saucier, Michel Pigeon, and Patrick Plante

Publication: Materials Journal

Volume: 87

Issue: 1

Appears on pages(s): 3-11

Keywords: air-entraining agents; air entrainment; concretes; field tests; freeze-thaw durability; plasticizers; stability; standards; Materials Research

DOI: 10.14359/2291

Date: 1/1/1990

Abstract:
Previous laboratory work has shown that the characteristics of the air-void system of air-entrained concretes can vary significantly between the initial mixing and the final casting, up to 90 min later. Addition of a superplasticizer (SP) can destabilize the air-void system, but this effect is extremely variable and is particularly related to the cement and the air-entraining agent used. This paper presents the results of field tests carried out to confirm the laboratory results. Eighteen mixes were made in ready-mix trucks, using three cements, two air-entraining agents, and two SPs. The results show that melamine and naphthalene-based superplasticizers can create important discrepancies in the air content versus the spacing factor relationship. It is concluded that concrete producers must be very careful when using SPs in air-entrained concrete because significant air-void system destabilization can occur without any significant air content variation. In-plant testing is highly recommended to verify the effect of a given combination of cement-air-entraining agent-SP, and a general procedure to do it is proposed.