Icy cylinders

Concrete Construction, July, 2003 by J.D. Robson

Regarding the letter from Frank Kozeliski concerning curing of cylinders ("Icy Cylinders," Jan. 2003, p. 16), I agree with the comment that it's important to know the min/max temperatures to which the cylinders have been exposed. On the other hand, the pail shown in the picture only has a bit of ice on the surface. This suggests that the water in the pail actually prevented the cylinders from freezing in an unheated area. The concrete strength may be slower getting there (low 7-day strengths), but there should be no permanent damage--provided the cylinders are handled very gently until they actually set.

Here are some pictures of the ends we trimmed off cylinders that actually did freeze. The ambient temperature was in the range of -13[degrees] to -22[degrees]F. The strength of the cylinders after the frozen ends were trimmed off was low (22 MPa, where 27.5 MPa was specified) but we did not core to correlate that to in-place strength. If you look at the photo on the right, (above) you can see the change in color at the concrete surface, with more subtle changes to almost 1.5 inches.

--J.D. (Dave) Robson

EBA Engineering Consultants Ltd.

Edmonton, Alberta