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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: Core Strengths of High-Strength Concrete
Author(s): George C. Hoff and Radoslav Elimov
Publication: Special Publication
Appears on pages(s): 705-732
Keywords: Drilling; fly ash; high-performance concretes; high-strength concretes;
offshore structures; silica fume
Abstract:The effects of varying L/D ratios and core size on the strength of cores from large elements of high-strength concrete (HSC) made both in the laboratory and the field were examined. One-hundred and fifty four cores (65 mm and 100 mm nominal diameters) representing 5 laboratory mixtures having moist-cured cylinder compressive strengths from 114 to 142 MPa at 5-years age and 101 cores (70 mm and 100 mm nominal diameters) representing an actual field placement of 28,150 m3 of concrete in an offshore concrete structure having continuously moist-cured compressive strengths at l-year from 88 to 92 MPa were evaluated. The results indicate that for 100 mm (nominal) diameter cores of HSC, there is no need to apply the ASTM C 39 correction factors to the observed strength of cores with L/D’s from 2.0 to 1.0. The use of cores with a smaller diameter (e.g., 70 mm) exhibit lower strengths (78% to 82%) than companion larger diameter cores and have a higher degree of variability and thus are not recommended for use with HSC. At early ages (e.g., 28-days), the observed strength of HSC cores may be very close to the strength of continuously moist-cured control cylinders. At substantially later ages (e.g. 5 years), the observed strength of the cores may be fairly close to the strength of air-cured control cylinders but be only 70% to 80% of the strength of continuously moist-cured cylinders.
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