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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: NDT Use in Evaluating the Form Removal Time for a Large Diameter Tunnel Concrete Lining
Author(s): T. R. Harrell
Publication: Special Publication
Appears on pages(s): 153-164
Keywords: concretes; form removal; nondestructive tests; penetration tests; thermocouples; tunnel linings; General
Abstract:A case history of methods used to evaluate the allowable form removal time for a large diameter tunnel concrete lining is presented. To meet schedule requirements, a concrete placement was to be made every alternate day. A triad of testing was done to evaluate the time at which the reusable, self-propelled, steel-skinned form could be stripped from an existing placement. This testing consisted of field-cured cylinders and nondestructive testing that included embedded thermocouples in the concrete placements and penetration-resistance testing. Reference curves and tables were developed for use in the form removal evaluation. Statistical methods were used on test data obtained from results of testing done with the actual concrete mix to be used in the placements. Control curves were then developed. Target values were selected to be used in determining when the concrete was of sufficient strength to allow for the form removal.
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