How do you control the strength of concrete?

The easiest way to add strength is to add cement. The factor that most predominantly influences concrete strength is the ratio of water to cement in the cement paste that binds the aggregates together. The higher this ratio is, the weaker the concrete will be and vice versa. Every desirable physical property that you can measure will be adversely effected by adding more water.

Although the above mentioned techniques have been proven to be effective, they might sometime entail higher costs.

Many a times it has been found that even when the concrete is of desired strength in the lab it may not give the necessary strength at site due to poor compaction techniques or less curing which can have disastrous effects on concrete strength. These small things can make a big difference.

Fibre reinforcement concrete has been in vogue for the past 80 years. The trend started with use of steel fibres and now synthetic fibres are used in concrete in dosages varying from .25 per cent on cement weight up to 10 per cent. Some of the obvious gains are its innate energy absorption capacity, reduced permeability and crack width and improving tensile strength. The fibre product has been tested and proved effective in minimizing crack width. The contrast between steel and synthetic fibres, the former was stiff and when used the outer layer of road surfaces got worn out. It could cause physical harm too. Such problems can be minimized by using polymer-based synthetic fibres which are flexible and provide good bonding with concrete.