Once the health risks associated with asbestos were discovered, there was a need to find a replacement for the substance in concrete and other building materials.
[8][9][10] This can occur in climates that are subjected to water or intense and repeated moisture, see Surfside Building Collapse.
If the fiber's modulus of elasticity is higher than the matrix (concrete or mortar binder), they help to carry the load by increasing the tensile strength of the material.
Longer length results in better matrix inside the concrete and finer diameter increases the count of fibers.
However, fibers that are too long and not properly treated at time of processing tend to "ball" in the mix and create work-ability problems.
The High Speed 1 tunnel linings incorporated concrete containing 1 kg/m3 or more of polypropylene fibers, of diameter 18 & 32 μm, giving the benefits noted below.
Care should be taken to ensure that local design code requirements are also met, which may impose minimum quantities of steel reinforcement within the concrete.
Micro-rebar has also been recently tested and approved to replace traditional reinforcement in vertical walls designed in accordance with ACI 318 Chapter 14.
When loaded to beyond the elastic range, HPFRC maintains crack width to below 100 μm, even when deformed to several percent tensile strains.
[28] Recent studies on high-performance fiber-reinforced concrete in a bridge deck found that adding fibers provided residual strength and controlled cracking.
The use of natural fibers has become a topic of research mainly due to the expected positive environmental impact, recyclability, and economy.