cube strengths 1

[PhilipWanless]

MOst standard concrete test cubes are either 150mm ( 6 inches ) or 100mm ( 4 inches ). The same concrete mix will give a different strength result at 28 days according to the size of mould used. Can anyone provide information about the magnitude of the difference obtained from different mould sizes ?

 

[Ron]

It will vary according to the mix properties, most particularly the size of the coarse aggregate. Check with ready mix supplier as they probably have correlations with many of their mix designs.

 

[ishvaaag]

If the strength of 15x30 cm (=6"x12&quot is 1

average strength for

cube 10 cm side (4&quot is 0.80
cube 15 cm side (6&quot is 0.80
cube 20 cm side (8&quot is 0.83
cube 30 cm side (12&quot is 0.90

source is

Hormigón Armado 7nth edition
Montoya, Meseguer, Morán
Gustavo Gili, Barcelona 1974

 

[drfefefe]

The ratio between the cubic resistence and de cylinder resistence have a average of 0.8, whatever was his size, but it has to be taken into acount that the mold size shall be at least three times the nominal maximun size of the coarse aggregate,also in the test is necessary use squares contact area faces.

Sicerely,

Federico

 

[SURYANARAYANA]

The percentage of the cement paste that goes into each mould filled with concrete, along with other factors such as particle size distribution of the aggregates used and method of packing will be the determining factors for obtaining a uniform compressive strength for all the cube samples. Also, the Universal testing machines pressure gauge gives varying results for different ranges of loads. It is desirable that the UTM be calibrated with proving rings for different ranges of loads, and a graph be plotted for an accurate compressive strength reading.