Concrete is unsuitable for compaction by a vibrator if it is

The approx. ratio of the direct tensile strength to direct compressible strength test is

For constant w/c ratio if the aggregate/cement ratio is reduced, the workability of concrete

Bulking of sand is

Setting time of cement increases by adding

For preparing ordinary concrete, the quantity of water used, is

The cement concrete in which high compressive stressed are artificially induced before its actual use is called

In order to have segregation in concrete, its dropping height should be less than