No fine concrete as the term implies is a kind of concrete from which the fine aggregate fraction has been omitted. This concrete is made up of only coarse aggregate. Cement and water. Very often only single size coarse aggregate of size passing through 20mm retained on 10mm is used. No fine concrete is becoming popular because of some of the advantages is posses over the conventional concrete.

Mix proportion

No fine concrete is generally made with the aggregate/cement ratio from 6:1 to 10:1 . Aggregate used are normally of size passing through 20mm and retain on 10mm. Unlike the conventional concrete, in which strength is primarily controlled by the water/cement ratio, aggregate cement ratio and unit weight of concrete. Fig show the relationship of compressive strength water/cement ratio and aggregate cement ratio for no fine cement.

Relationship of compressive strength W/C and A/C for no fine concrete

No fine concrete does not pose any serious problem for compaction. Use of mechanical compaction or vibratory method are not required. Sample rodding is sufficient to full compaction.

The bond strength of no fine concrete is very low and therefor reinforcement is not used in conjunction with no fines concrete.

However if reinforcement is required to be used in no fine concrete, it is advisable to smear the reinforcement with cement paste. To improve the bond and to protect it from rusting.