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Title: Use of Polymeric Microspheres for Providing Resistance to Freeze-Thaw and Salt Scaling

Author(s): Michael D. A. Thomas

Publication: Web Session

Volume: ws_S18_MicroSpheres_Thomas.pdf

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 3/26/2018

Abstract:
This paper reports the data from a laboratory and field test program to evaluate the freeze-thaw and deicer-salt scaling resistance of concrete produced with hollow polymeric microspheres as an alternative to traditional entrained air bubbles. Concrete mixtures were produced with two levels of microspheres (0.75 and 1.00 % by volume) and the performance was compared with a control mix cast with the same cement content and w/cm, but with 6% entrained air rather than microspheres. Testing included laboratory freeze-thaw (ASTM C 666 – Procedure A) and salt scaling (ASTM C 672) tests. Concrete slabs (24 x 24 x 4 inches) were placed on UNB’s exposure site in Fall 2013 where they are subjected to frequent applications of deicing salts. Concrete beams (6 x 6 x21 inches) were placed at the mid-tide level of a marine exposure site in Summer 2014 and are exposed to seawater, wet-dry cycles, and approximately 100 freeze-thaw cycles per year. The laboratory results indicate that the concrete with microspheres has equivalent freeze-thaw and scaling resistance, and higher compressive strength compared with the control. The increased strength is, of course, the result of the lower air content when the microspheres are used. Concrete slabs and beams have shown no signs of deterioration after, respectively, 4 and 3 winters on the UNB exposure site and the tidal marine site. Potential mechanisms to explain the function of the microspheres are discussed.