Concreting of Thick Sections in the Tropics

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Title: Concreting of Thick Sections in the Tropics

Author(s): C. T. Tam

Publication: Special Publication

Volume: 139

Issue:

Appears on pages(s): 143-156

Keywords: beams (supports); cracking (fracturing); heat of hydration; differential thermal analysis; hot weather construction; humidity; insulation; porosity; temperature; thermal stresses; thermocouples; thick sections; wind velocity; Materials Research

Date: 9/1/1993

Abstract:
Concreting of thick sections involves large volume placements for cases such as foundation rafts and beams of exceptional dimensions, which frequently occur in highrise construction in Singapore. The heat of hydration generated in using concrete of structural grade is much higher than that associated with mass concreting of dams. For any thick section, The temperature differential between the warmer interior and the cooler surfaces gives rise to different thermal strains which may be sufficiently high to result in cracking. In hot climates, it also leads to very high peak temperatures (often above 70 C). Typical case histories of such placements in tropical climates are presented, including the mixtures used and the overall dimensions of the members. For two of the cases, the measured temperature histories are compared with those from numerical simulation using finite elements. The requirements of concrete mix design and precautions to be considered in relation to the planning and execution of large placements as well as the use of insulation to control temperature differentials are discussed.