Concrete Cube Test vs. Cylinder Test 1

[StructureMan44]

For those with the experience, is the concrete cylinder test more accurate/reliable than the concrete cube test? I had never heard of the concrete cube test but a client is requesting it on an international project. It seems very similar to the concrete in that it also tests compressive strength:

http://www.qemsolutions.com/news/a-simple-guide-to-concrete-cube-testing

 

[concretemasonry]

StructureMan44 -

What is the local material standard/method for testing and are you talking about laboratory prepared samples or site samples? Smaller saples have problems with coarse aggregates used or specified.

If the local method is for smaller cubes, you may not find a testing machine capable of conducting proper testing. The size of the compression area is very important. I had a situation where I needed some hollow 8x8x16 concrete block (high strength) to be tested and the 2 machines (Tinius Olsen) used by the lab for daily testing of high strength concrete cylinders could not deliver accurate results because the thickness of the platen (too flexible) was inadequate for the sample horizontal dimensions. - A new, thicker and stiffer platen had to be ordered before 28 day tests and all it took was a 10 second look at the test photos.

Personally, I do not like the cubes (1:1 h/t) because there is always some friction/restraint the force a 45 degree shear plane or confined compression failure. A cylinder usually has a 2:1 h/t ratio that provides results (30 degree or so) shear failure compatible with the concepts used in most code developments. The lab I dealt with was willing to take photos of the cylinder breaks upon request that could highlight erratic results or sample preparation.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[Ron]

StructureMan....in the US, cylinders are the norm. In many other countries, cubes are the norm. I prefer cylinders, but there has been enough testing and research on cubes to consider them valid as well.

 

[yaschief]

General Rule in USA is Cylinders (6"x12" or 4"x8") for Concrete and Cubes (1"x1" or 2"x2") for Mortar/Grout with some labs doing Cylinders for Grout (3"x6").