00131691

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http://onlinepubs.trb.org...s/trr/1975/558/558-005.pdf

https://scholar.google.co...kley&publication_year=1975

The C.N. Tower will be the highest free-standing structure in the world. The foundations contain 10,000 cu yd 7646 cu m of low-heat cement concrete, and accelerated testing was used throughout the concreting period. The slip-formed concrete superstructure is 1,464 ft (450 m) high and contain 40,000 cu yd (30 580 cu m) of concrete. The accelerated test used during slip forming was the 48-hour autogenous test devised by Smith and Tiede. The last 3 months of slip forming were carried out from December 1973 to February 1974, the coldest period of the Canadian winter. Ambient conditions as low as 1 F (-17 C) were experienced, and wind-chill factors at heights above 1,000 ft (305 m) significantly increased the low-temperature effects. Maturity testing was done to check that, as the slip from rose, the concrete exposed to winter conditions achieved adequate strength. Thermocouples inserted during every shift were monitored at intervals throughout each 24-hour period, and in-place strengths were calculated. Monitoring continued until acceptable strengths has been achieved at each level. Evaluation were based on cores drilled from the structure and cylinder tests.

Publication of this paper sponsored by Committee on Mechanical Properties of Concrete.Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01411416

pp 45-49

1975

Transportation Research Record

54th Annual Meeting of the Transportation Research Board

0309024668

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Figures (5)

Accelerated tests; Cold weather construction; Concrete; Concrete tests; Core samples; Field tests; Low temperature; Monitoring; Slip form pavers; Specimens; Strength of materials; Thermocouples

Maturity

Highways; Materials

TRIS, TRB

Jun 5 1976 12:00AM

• ACCELERATED METHODS OF ESTIMATING THE STRENGTH OF CONCRETE
• ACCELERATED SPLITTING-TENSION TEST FOR DETERMINING POTENTIAL 28-DAY SPLITTING TENSILE STRENGTH AND MODULUS OF RUPTURE OF CONCRETE
• ACCELERATED TESTING FOR PREDICTION OF 28-DAY STRENGTH OF CONCRETE
• CANADIAN EXPERIENCE IN THE USE OF THE MODIFIED BOILING METHOD
• DEVELOPMENTS IN THE PREDICTION OF POTENTIAL STRENGTH OF CONCRETE FROM RESULTS OF EARLY TESTS
• EARLY STRENGTH TEST FOR QUALITY CONTROL OF CONCRETE
• EVALUATION OF A CHEMICAL TECHNIQUE TO DETERMINE WATER AND CEMENT CONTENT OF FRESH CONCRETE
• FIELD EVALUATION OF EXPANDED POLYSTYRENE MOLDS FOR SELF-CURED, ACCELERATED STRENGTH TESTING OF CONCRETE
• PERMEABILITY TESTING OF PLASTIC CONCRETE
• PRACTICAL APPLICATION OF MATURITY CONCEPT TO DETERMINE IN SITU STRENGTH OF CONCRETE
• PREDICTION OF STRENGTH DEVELOPMENT IN CONCRETE STRUCTURES
• STRENGTH TESTS AT EARLY AGES AND AT HIGH SETTING TEMPERATURES