established the relationship between the compressive strength of cubic specimens and the compressive strength of the cylinder, with a correction factor of about 0.94 for converting the cube strength to cylinder strength
. They also concluded that the slight difference in the compressive strength of the specimens with different shapes could be minimized by the regularization mortar at the end of specimens.
The designed strength of 21MPa (3 ksi) was obtained with a nominal mix ratio of concrete, using this aggregate size (The designed strength is based on 28 Days Compressive Cylinder Strength).
The concrete mix proportion is strength based and the target strength is not less than 21MPa (3 ksi) 28 days compressive cylinder strength.
The compressive strength thus obtained is the standard cylinder strength
of the concrete concerned.
EC4 requires the characteristic concrete cylinder strength, [f.sub.ck], to be at least 20 MPa and not more than 50 MPa "unless its use is appropriately justified".
For rectangular cross-section columns of agreement is good except when the concrete cylinder strength was greater than 75 MPa (strength greater than 50 MPa is not allowed in EC4), when many tests failed below the strength predicted by EC4.
I sure hope they don't; even if cylinder strength
is not a concern, other things are.
The model established in this study is based on the premise of the cylinder strength of concrete with the diameter of 150 mm, using the size effect reduction model ((6)-(7)) to verify the cylinder strength of concrete ([f.sub.cD]) in steel tubes of different diameters.
This size effect on the three components of the axial bearing capacity of a circular CFT is reflected through an SEL that incorporates a factor for the reduction in concrete cylinder strength with size R, the coefficient of confinement under triaxial compression K, and both hoop and vertical factors for the steel tube ([G.sub.[theta]] and [G.sub.z]).
To develop relationship between 28.5h accelerated compressive cylinder strength
and 7-D and 28-D cylinder strength
of normal strength concrete tentative mix proportions of concretes and their w/c ratios were selected and designated by Mix 1 to Mix 24 in this study.
The variation in the average cube and cylinder strengths
of HPFRC containing Basalt fibers was found to be in the range of [+ or -] 4% compared to the average compressive strength of the control specimens.