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
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.