Title: Cylinder vs. core strength

Author(s): Ava Szypula and Jacob S. Grossman

Publication: Concrete International

Volume: 12

Issue: 2

Appears on pages(s): 55-61

Keywords: compressive strength; concrete cores; cracking (fracturing);

DOI:

Date: 2/1/1990

Abstract:
The objective of the laboratory research was to determine the nominal compressive strength of an in situ concrete slab for which field data was not available. Cores that had been taken from slabs that were subjected to flexural and restrain cracking indicated low compressive strengths and a large range of results. The construction of the mock-up slab attempted to duplicate the concrete properties (established by petrographic analysis), the field construction procedure and the curing conditions. The mock-up slab study indicated that field cores, taken from flexural members that are supporting loads and/or are restrained by stiff supports, cannot be relied upon to determine the nominal compressive strength of the concrete because microcracks and other larger cracks are present to adversely reduce the measured capacity.