Introduction

Fiber reinforced concrete (FRC) is a composite material consisting of concrete reinforced with fibrous materials which increases its structural integrity. Fibers used can be steel fibers, synthetic fibers and natural fibers. When fibers are added to concrete, they act as crack arrestors and controls crack width. This enables fiber concrete to have multiple micro cracks instead of a few large cracks.

Types of Fibers Used

Steel Fibers
Steel fibers are the most common type used in Fiber Reinforced Concrete. They are made of steel in various shapes such as flat, hooked end or crimped. Steel fibers improve concrete’s ductility, energy absorption capacity and post-cracking behavior. They significantly increase a concrete’s tensile strength and prevent cracks from propagating. Due to their high strength, steel fibers are ideal where high reinforcement is needed. They are also corrosion resistant compared to normal steel rebar.

Synthetic Fibers
Synthetic fibers such as polypropylene fibers and polyvinyl alcohol fibers are also widely used in fiber concrete. These fibers have a higher tensile strength than steel and are lighter weight. Polypropylene fibers in particular improve impact, abrasion and shatter resistance of concrete. They are alkali resistant and have good adhesion with concrete. Synthetic fibers provides improved structural performance at a lower cost compared to steel fibers and has less risk of corrosion.

Natural Fibers
Natural fibers from materials such as cellulose, wool, jute and sisal can also be used to reinforce concrete. These are renewable, biodegradable and have low density. However, their strength is not comparable to steel or synthetic fibers. Natural fibers find application in non-structural fiber concrete used in precast panels, pavement blocks, mortars etc.

Advantages of Fiber Reinforced Concrete

Improved Tensile Strength
The most significant benefit of Fiber Reinforced Concrete is the large increase in its tensile strength compared to plain concrete. Fibers provide multiple crack arrestors and controls crack width effectively. This improves concrete’s post-cracking behavior and ductility substantially. With fibers, concrete can take 50% more tensile load before cracking.

Higher Durability
Presence of fibers decreases permeability of hardened concrete. It reduces penetration of water, chloride ions and other chemical agents into concrete. This makes fiber concrete highly durable even under severe environmental conditions. Fibers also reduces shrinkage cracks further strengthening its durability.

Enhanced Impact Resistance
FRC exhibits much higher resistance to impact, shocks or dynamic loading conditions compared to concrete without fibers. Fibers bridge across cracks arresting their growth and propagation. This enables FRC to absorb higher energy under impact loads.

Reduced Plastic Shrinkage Cracking
During hydration process moisture migrates from interior to surface of concrete causing plastic shrinkage cracks. Addition of even 0.2% volume fraction of fibers is sufficient to substantially reduce such plastic cracking of concrete.

Applications of Fiber Reinforced Concrete

Thin industrial slabs
FRC slabs are widely used as flooring and paving material in commercial and industrial buildings. Its ability to span over longer distances without cracking makes it suitable for thin flat slabs even without reinforcement. This simplifies formwork and facilitates easy construction.

Pre-cast components
Precast concrete elements such as hollow core slabs, wall panels, pipes, manhole covers etc sees extensive use of fiber reinforcement. It allows fabrication of thin walled components with high dimensional stability and durability.

Overlays and repair works
FRC is ideal for repairing cracks in existing structures or creating overlays on pavement or bridge decks. It bonds well with substrate and seals cracks permanently due to its high tensile strength and flexibility.

Tunnel linings
Fibers helps concrete lining of tunnels withstand soil pressure and ground movement induced stresses and cracking. Steel fiber concrete in particular is suitable where structures needs to withstand significant loads.

Shotcrete applications
Shotcrete or sprayed concrete is commonly applied with fiber addition on walls of tunnels, slopes, mines etc. Fibers makes shotcrete flexible to take uneven contours and self-supporting even in thin layers.

Slabs on ground
Fiber reinforced slabs laid directly over soil forms crack resistant flooring for houses, industrial buildings, warehouses etc. Fibers prevents shrinkage and settlement related cracking of these slabson-grade

Fiber reinforced concrete undoubtedly offers several benefits that enable its wide usage for various structural and nonstructural applications. Its ability to control cracking under tensile, impact or dynamic loads and improved post-cracking performance are major advantages driving new trends in construction. With ongoing research improving fiber concrete technology, its use can be further expanded for durable infrastructure development globally.

*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it.