Concrete has a natural tendency to crack. Over the years, this condition has been accepted as natural to its use. Concrete cracks for only one reason – stresses exist which exceed the strength of the concrete at a specific time. For the most part, stresses caused by external forces can be overcome by the use of higher strength concrete. Internal cracks within the concrete are much harder to control due to their unpredictable nature.
The most common type of intrinsic cracking occurs during the plastic state caused by drying shrinkage. These cracks generally occur in the first 24 hours after placement. Settlement and shrinkage cracks may not be apparent until later. Plastic shrinkage cracks often pass through the entire slab, lowering the integrity of the slab before the concrete has gained its desired strength. Fibers, introduced into the concrete at the time of batching, greatly reduce the formation of plastic shrinkage and settlement cracks. The fibers are uniformly dispersed throughout the concrete, providing an excellent secondary reinforcement. The use of fibers in concrete has other benefits, not to mention the least of which is cost reduction due to the elimination of the need for welded wire fabric as a secondary reinforcement.
The benefits of using fiber-reinforced concrete:
- Much less susceptible to damage caused by plastic shrinkage and settlement
- Eliminates need for secondary reinforcements like welded wire fabric
- Distributes evenly throughout concrete, unlike wire that can settle to bottom
- Maximizes productivity and profitability
- Provides superior finished product