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In many practical measurements, the compressive strength, f, of standard cubic or cylindrical specimens are considered as actual strength of concrete used in structural elements. However, there are numerous parameters which cause the standard compressive test not to represent actual strength of casted materials, e.g. concrete casting, environment and curing conditions, vibrations and so on. The mentioned difference is, more remarkable in shotcrete which is used in 3D light weight sandwich panels. In this system the thickness of shotcrete wythe is about 50 mm which is minimum based on ACI recommendation for provision of core specimens. The presented work tries to show the estimation of compressive strength of standard cylinder and concrete cores taken from 3D standard elements in 60 specimens and, also, to manipulate experimental relations between these two methods.
The current study is concluded with a reduction factor, which shall apply to the standard cylinders strength, f , as to achieve the actual compressive strength