Journal Published Online: 17 July 2019
Volume 8, Issue 3

Properties of Nanosilica-Modified Concrete Cast and Cured under Cyclic Freezing/Low Temperatures

CODEN: ACEMF9

Abstract

Cold weather concreting is one of the most challenging problems facing concrete placement in many regions. For example, in Canada, low temperatures limit the construction season to a few months, usually between May and September. The incorporation of nanosilica in concrete, which has vigorous reactivity because of its ultrafine surface area, may enhance the hydration process and properties of concrete cast at low temperatures; however, this has not been substantiated. Therefore, this study focused on developing nanomodified concrete mixtures that were mixed, placed, and cured at cyclic temperatures (−5°C and 5°C), targeting applications in early fall and late spring periods in North America. The study followed the design of experiments modeling approach to test 15 concrete mixtures based on the response surface method. Three parameters were considered in the model: incorporation of fly ash (up to 25 %) and nanosilica (up to 4 %) as well as a combination of two types of antifreeze admixtures (calcium nitrate and nitrite). The mixtures were assessed based on setting time (placement), 3- and 28-day compressive strengths (hardened properties) and absorption (infiltration of fluids). Moreover, mercury intrusion porosimetry, thermal analysis, and scanning electron microscopy were conducted to characterize the microstructural features. The results showed that nanosilica, even with the inclusion of fly ash, significantly enhanced the overall performance and development of the microstructure of concrete mixed, cast, and cured at cyclic freezing/low temperatures. Thus, nanomodified concrete has promising potential for extending the construction season during early fall and late spring periods in cold regions.

Author Information

Abayou, A.
Department of Civil Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
Yasien, A. M.
Department of Civil Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
Bassuoni, M. T.
Department of Civil Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
Pages: 20
Price: $25.00
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Stock #: ACEM20190013
ISSN: 2379-1357
DOI: 10.1520/ACEM20190013