Title: Heat Curing of Concrete With and Without Condensed Silica Fume--Effect of Early Temperature History on Compressive Strength

Author(s): P. H. Laamanen, K. Johansen, B. P. Kyltveit, and E. J. Sellevold

Publication: Symposium Paper

Volume: 132

Issue:

Appears on pages(s): 1045-1060

Keywords: admixtures; aggregates; compressive strength; silica fume; curing; temperature; Materials Research

DOI: 10.14359/2394

Date: 5/1/1992

Abstract:
It is well known that curing concrete at elevated temperatures reduces the final compressive strength. The reduction depends on the temperature regime as well as the concrete composition. This program was based on recent data indicating that concrete containing condensed silica fume suffers less strength loss if a strength of about 10 MPa is reached at 20 C before heating. In this investigation, concrete characteristics were w/c + s = 0.30, 0.45, and 0.60 with and without 8 percent condensed silica fume. The temperature regime was to transfer specimens at 40 and 60 C, after delay times at 20 C. The delay times corresponded to strengths of about, 0, 3, 6, 9, 12, and 16 MPa. After 6 days, all specimens were cooled to 20 C and tested at 28d. The results show that the delay period had no significant influence on the final strength, except for the specimens with zero delay. The rest suffered some strength reduction compared to 20 C references, about 15 percent for w/c + s = 0.60, and less than 10 percent for the others. The reductions at 60 C were slightly greater than at 40 C. Concretes containing condensed silica fume generally suffered the smallest strength reductions.