Steel Fiber Reinforced Concrete & High-strength concrete

Steel Fiber Reinforced Concrete :

It has been recognized that the addition of small closely spaced and uniformly dispersed fibers to concrete would act as crack arrested and would substantially improve its static and dynamic properties. This type of concrete is known as fiber reinforced concrete.

It can be defined as a composite material consisting of mixtures of cement, mortar or concrete and discontinuous, discrete, uniformity dispersed suitable fibers.

Steel fiber is one of the most commonly used fiber. The diameter of steel fiber may vary from 0.25 to 0.75 mm.

High-strength concrete :

It has a compressive strength greater than 40MPa. High-strength concrete is made by lowering the water-cement(W/C)ratio to 0.35 or lower. Often silica fume is added to prevent the formation of free hydroxide crystals in the cement matrix, which might reduce the strength at the cement-aggregate bond. Low W/C ratios and the use of silica fume make concrete mixes significantly less workable, which is particularly likely to be a problem in high-strength concrete applications where dense rebar cages are likely to be used. To compensate for the reduced workability, super plasticizers are commonly added to high-strength mixtures. Aggregate must be selected carefully for high-strength mixes, as worker aggregates may not be strong enough to resist the loads imposed on the concrete and cause failure to start in the aggregate rather than in the matrix or at a void, as normally occurs in regular concrete.