Journal
CEMENT AND CONCRETE RESEARCH
Volume 101, Issue -, Pages 144-158Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.cemconres.2017.09.001
Keywords
De-icing salts; Calcium oxychloride; Magnesium oxychloride; Wet/dry cycles; Fly ash; Nanosilica
Funding
- Natural Sciences and Engineering Research Council of Canada [RGPIN/4024-2014]
- University of Manitoba
- City of Winnipeg [317756]
Ask authors/readers for more resources
Formation of complex salts (oxychlorides) has been suspected for causing chemical degradation of concrete in cold regions. In this study, conditioned mode (controlled temperature and relative humidity) environmental scanning electron microscopy was specifically used to minimize changes in the crystal structures of oxychlorides phases and thus reliably capture their unaltered morphology and existence/effects on concrete exposed to different de-icing salts under two different environmental conditions (constant low temperature and wetting/drying (W/D) cycles). Formation of acicular flattened blades of 3- and 5-form magnesium oxychloride (MOX) and tiny fibrous crystals as well as subhedral pseudo-hexagonal calcium oxychloride plates (COX) were found in deteriorated concrete specimens, depending on the type of solution. The reversible formation of hydrous and anhydrous COX during W/D cycles had a significant effect on aggravating the kinetics of damage of concrete in this exposure. The combined salt (MgCl2 + CaCl2), which simulates using a synergistic maintenance and protective strategy for concrete pavements in winter, was the most aggressive solution; thus, this practice should be cautiously reconsidered. The incorporation of 30% fly ash had a pronounced effect on improving the concrete resistance to damage as reflected by sound mechanical properties and longevity. Also, the performance of concrete was much enhanced when an innovative supplementary cementitious material, nanosilica, was incorporated in the cementitious system.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available