Title: Determination of Chloride Diffusion Coefficient of High-Performance Concrete by Electrical Potential Technique

Author(s): T. Sugiyama

Publication: Symposium Paper

Volume: 163

Issue:

Appears on pages(s): 339-354

Keywords: chlorides; portland cement; silica fume; superplasticizers; Materials Research

DOI: 10.14359/1348

Date: 8/1/1996

Abstract:
Electrical potential technique was used as an accelerated testing method to determine the chloride diffusion coefficient of high-performance concrete. An electrical potential difference of 15 volts was applied to a disc-shaped concrete specimen of 50 mm in thickness. This direct current voltage increased the flux of chloride ions migrating through the concrete and permitted the determination of the chloride diffusion coefficient (D CL) within three to four weeks of the testing period. The water-to-cementitious materials ratio (W/C) had a significant effect on D CL, where the relationship between W/C and D CL was expressed as D CL={0.32EXP[5.47(W/C)]} x 10 -8 cm 2/s for normal concrete without any mineral additives. Concretes with five and 10 percent silica fume replacements for ordinary portland cement were also tested and had D CLs equal to 3.14 and 2.99 x 10 -8 cm 2/s, respectively, after a 28- day moist curing period. These D CL values were lower than that of concrete containing only portland cement, being 4.3 x 10 -8 cm 2/s for concrete with the same W/C of 0.45 and a moist curing time of 28 days. Furthermore, super- workable concrete which had a W/C of 0.3 and was moist cured for 28 days had a D CL of 1.97 x 10 -8 cm 2/s.