Composition of Glass Fiber Reinforced Concrete (GFRC)

Glass fiber reinforced concrete composites contain high strength glass fibers that are surrounded by a cementitious medium. In this shape, both the fibers and the environment maintain their natural individual chemical characteristics. However, the concrete produced has improved resultant properties that cannot be attained if either of the components is used individually. The glass fibers are the main elements that carry the load, while the enclosed matrix keeps the fibers in the preferred position and direction. The medium facilitates transfer of the load on the fibers, and shields them from the damage due to environment. Glass fibers can be integrated into the matrix either in constant or irregular lengths. The most widespread shape in which glass fiber reinforced composites are used in structural applications is known as laminate. This form is achieved by consolidating fine fiber layers and a matrix into the desired size. The orientation of fiber in each layer, and the stacking sequence of the layers, can be used to produce a range of mechanical properties of the composite materials.

All these properties are combined with the fact that GFRC looks like solid concrete, although it weighs only one-third of the original solid concrete weight. This makes it ideal for outdoor or indoor applications where lightweight and durable concrete is needed. Such applications may include decorative structures, fountains, domes, planters, etc.

Glass fiber consists of 200-400 individual filaments, lightly bonded in order to form a stand. These stands can then be chopped into various lengths and be used for a variety of applications. The main industrial application of glass fibers is cement or mortar matrices reinforcing, used for thin-sheet products manufacture. The conventional mixing techniques for concrete only allow about 2% (by volume) of fibers of a length of 25mm to be used. The most common type of glass fibers used for general applications is e-glass. Polymers may also be added in the glass fiber mixes in order to improve physical properties such as moisture movement.

GFRC is an engineered material. Its properties can change depending upon the design of mix, fiber content, and the techniques used for manufacture. The use of GFRC has become popular due to its numerous favorable properties:

• GFRC has been tested in the laboratory and also in the actual installations, and can be anticipated to survive as long as pre-cast concrete. In numerous environmental conditions, like when exposed to salts or moisture, GFRC is likely to function better due to the absence of steel reinforcement that may corrode.
• Relatively light in weight compared to the traditional stones. Its installation is fast and comparatively simple.
• GFRC has the characteristics to be cast into almost any shape.
• GFRC consists of materials that are unlikely to burn. The concrete takes the role of a thermal regulator while exposed to fire and protects the materials from the flame heat.
• GFRC is thin and strong, with weight being 75% to 90% less compared to solid concrete. Less weight facilitates easy and rapid installation, and also decreases the load applied on the structure. The light weight and tough material also minimizes the transportation expenditures, permits flexibility in design, and reduces the impact on environment.
• Superior strength enhances the ability to endure seismic loads.
• GFRC is less vulnerable to weather effects and more resistant to freeze thaw than the normal concrete.

The elasticity and density of the GFRC is greater than precast concrete. The cement to sand ratio for GFRC is approximately 1:1, while for precast concrete it is 1:6. The glass fibers included to reinforce the concrete produce considerably greater impact strength and lower permeability to water and air than precast concrete. GFRC looks like a natural stone and permits the designer greater flexibility in form, color, and texture.