Pessimum effect of externally applied chlorides on expansion due to delayed ettringite formation: Proposed mechanism

Journal Article · Sat Apr 15 04:00:00 EDT 2006 · Cement and Concrete Research

DOI:https://doi.org/10.1016/J.CEMCONRES.2005.1· OSTI ID:20793283

Ekolu, S O ^[1]; Thomas, M D.A. ^[2]; Hooton, R D ^[1]

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1. Department of Civil Engineering, University of Toronto, 35 St. George Str, Toronto, ON, M5S 1A4 (Canada)
2. Department of Civil Engineering, University of New Brunswick, P.O. Box 4400, Fredericton, N.B., E3B 5A3 (Canada)

Mortars and concretes were subjected to a heat treatment cycle consisting of a pre-set period of 4 h at 23 deg. C followed by accelerated curing at 95 deg. C prior to storage at room temperature in water or limewater, 0.5 M, 2.8 M sodium chloride solutions. It was found that the specimens stored in 0.5 M sodium chloride solution gave a much greater expansion than those stored in limewater or 2.8 M sodium chloride solution. This pessimum influence of chlorides on expansion due to delayed ettringite formation deviates from the commonly held view that chlorides mitigate sulphate attack in concretes. The mechanism of the pessimum effect of chlorides on expansion due to delayed ettringite formation, and the final products of the associated phase transformations have been proposed. X-ray diffraction and differential thermal analysis techniques were used to follow phase transformations.

• OSTI ID: 20793283
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Journal Issue: 4 Vol. 36; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CONCRETES
CURING
DIFFERENTIAL THERMAL ANALYSIS
EXPANSION
HEAT TREATMENTS
MORTARS
PHASE TRANSFORMATIONS
SODIUM CHLORIDES
SOLUTIONS
STEAM
SULFATES
TEMPERATURE RANGE 0273-0400 K
WATER
X-RAY DIFFRACTION