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 What is GFRC and why should I care about its use in a barrier system?

GFRC – "glass fiber reinforced concrete" is actually cement mortar with countless strands of embedded glass fiber; it is a true composite material. It does not have the graded rock aggregates or steel-reinforcing bars normally associated with concrete.

The principal material asset of GFRC is tensile strength or the ability to have strength when stretched. This tensile strength characteristic also creates dramatically enhanced impact strength. It shares equally the two primary assets of conventional concrete, which are compressive strength and longevity.

Conventional concrete has the trait known as "brittle failure" because it has a semi-crystalline structure, which tends to shatter on impact. This is especially dangerous when subjected to explosive force because ballistic debris is created which can create significant collateral damage.

This is not the case with GRFC, as it does not experience brittle failure. The glass fiber tends to hold the material together because the fibers are dispersed randomly and lay in all directions within the material matrix. GFRC has a dramatically reduced ballistic debris profile.

See section on - Physical Properties of GFRC <pdf>

GFRC is less expensive than precast or cast in place concrete if three dimensional shapes are desirable. This is the case because:

1. The tooling costs less because it does not have to hold the weight of the wet castable concrete (usually about 10 times the weight of GFRC) and does not require an inner mold or plug in shapes requiring an open or hollow area.

2. The finish or appearance need only be in the face coat of the GFRC while with precast or cast in place concrete, it needs to be throughout the entire mix.

3. Three dimensional detail is much easier to accomplish in GFRC (in fact, more intricate detail is possible) because the wet mix does not need to be vibrated as does conventional concrete in order to remove the excess air and water from the undercut shapes in the mold.

Three dimensional shapes are desirable for a barrier not only for aesthetic purposes but also to take advantage of the enhanced ability for a 3-D shape to create "progressive resistance" and / or diversion to the impact of a moving vehicle.