concrete strength

[dai]

Has any one experianced a recorded crushing srength from a cube of belowe strength at 28 days if the the specefication of concrete strenth was C35 and the recorded slump taken on site was between 75 and 100

 

[Ginger]

Yes.

However, this does not sound the death knell for your structure. The acceptance of concrete is calculated on a statistical basis. If you read your design code there will be an acceptable level of cube failures. You need to record ALL of the cube results you have ( there is a minimum number of results required to make a valid population). You then undertake a statistical analysis based on the mean plus or minus a set number of standard deviations. This will then tell you the number of results which can fall below a given strength level.

Regards Andy Machon