Thoughts on Curling in Plain and SRA Concrete Slabs: Moisture Gradients, Surface Tension, and Viscosity

• Published in: CONCREEP 10 pp. 327 - 331
• Main Author: Weiss, W. Jason
• Format: Book Chapter
• Language: English
• ISBN: 0784479348; 9780784479346
• DOI: 10.1061/9780784479346.038

This paper is part of the mini-symposium on the interplay between water and shrinkage. The paper provides a short discussion of observations from a recent neutron radiography experiment where radiography was performed on plain concrete and concrete containing a shrinkage reducing admixture (SRA) when each sample was exposed to drying. While the results of the radiography test provided information on the moisture content and degree of saturation, the goal of this paper is to relate the moisture (degree of saturation) gradients, the relative humidity gradients, the shrinkage gradient and a corresponding stress gradient. The work provides evidence for the reduced curling that is often seen in concrete containing SRA. The reduced curling with SRA appears to be a combination of the reduced surface tension that limits shrinkage and the increased viscosity that reduces fluid flux.