Concrete Technology Aspects of CN Tower

by John A. Bickley, Vice Pres. and General Mgr.; Construction Testing Services Ltd., Toronto, Ontario, Canada,

Serial Information: Journal of the Construction Division, 1975, Vol. 101, Issue 1, Pg. 201-212

Document Type: Journal Paper


The Canadian National Tower will be 1,805 ft high when finished. The bottom 1,500 ft of the tower is made of post-tensioned slip-formed concrete. The foundations contain about 10,000 cu yd of concrete and the slip-formed superstructure contains about 40,000 cu yd. Using type IV cement concrete and mixtures of type IV and and type I cement concrete heat-rise problems were minimized, high inplace strengths were achieved, and slip-form speeds up to 24 ft/day were reached. Slip-form concreting was carried out successfully in extremes of weather conditions from July, 1973, to February, 1974. A very high degree of control was realized. This produced concrete of great uniformity with greater than specified strength but with relative economy. The accelerated testing carried out gave quality assurance for all concrete with 48 hr of mixing. It proved to be invaluable in confirming strength and uniformity of concrete and in the psychological value it had to all involved.

Subject Headings: Strength of materials | Concrete | Cement | High-rise buildings | Tension | Foundations | Superstructures | Mixtures

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