In China, the allowable tolerance is ±2.0%.

It depends on the materials you are using.

following

Hi Weifeng,

could you please provide me with a reference (if it is in English).

Kind regards,

Dear Amir,

thank you for your response. Could you please elaborate it? What kind of materials properties may affect on this matter? Is there any reference for that?

Cheers

Dear Ebrahim many research has be done on but Black cotton soil and Lateritic soil to check their adequacy as a fill material or a liner materials for sanitary land fills and most times the strength of the soil still falls within the prescribed value at -2% to +2% of the optimum meaning that at the dry side and wet side of the optimum. when you have your optimum moisture content as 18% it means that the minimum you can go below is 16% and the maximum you can go above during field work is 20%.

The main factor which affects to the moisture content, depends on the fine materials are using in the mixes. Some previous studies explained the value of the tolerance in moisture content at ±2.0%.

In China, it is ±2.0% according the specification.

Soil properties, gradation curve, compaction curve and soil type are all important factors in deciding! However, previous work done in this field suggest that plus-minus 2 of the OMC would be safe.

The acceptable range for moisture content is OMC in lab +,- (2%). However, for the degree of compaction (Dry density in the feild/Max dry density in the lab) it depends on the type of road and for a highway it shall be greater than 96%.

Different factors can affect this decision but the tolerance would be +/_ 2%