Glass fiber reinforced concrete (GFRC) comprises hydration products of cement, or cement plus sand, and the glass fibers. Glass fibers are used are used as reinforcement for concrete.
Glass fibers were first used to reinforce cement and concrete in Russia. However they were corroded by the highly alkaline Portland cement matrix. Therefore, alkali resistant glass fibres have been subsequently developed in UK and other countries.
Glass fibers are available in the form of continuous rovings, chopped strand mats, cranette, wool, ropes and woven fabric. Glass fibers coated with epoxy resin compounds have also been tried out to protect them from alkali attack by Portland cement.
Preparation of Glass Fiber Reinforced Concrete (GFRC)
Glass fibers of 10mm to 50mm in length and a few microns in diameter can be added up to 5% by weight and premixed with cement and water in a pan or a paddle mixer. Small quantities of lubricating admixtures, such as polyethylene oxide or methyl cellulose may be added into the mix. The resulting mix may be sprayed or cast into the moulds.
The products can also be produced either by extrusion or by injection-moulded process. In some of the processes, rovings can be chopped in-situ and sprayed simultaneously with a slurry of suitable consistency on a mould of production. This is very effective and convenient for casting shell roofs and sheets.
Properties of Glass Fiber Reinforced Concrete
Addition of glass fibres of about 10% by volume increased the tensile strength by roughly two times, and the impact resistance by about 10 times. The cyclic loading tests conducted on glass fibre cement laminates showed fatigue resistance of Glass fiber reinforced concrete (GFRC) roughly comparable with that of Steel fiber reinforced concrete (SFRC).
Uses of Glass Fiber Reinforced Concrete
Uses of glass fibers in concrete is very limited because they suffer severe damage and loss of strength due to abrasion and impact forces generated during movement of aggregates in mixer.
Considerable attention has been paid for thorough understanding of the mechanical properties and performance characteristics of GFRC in the design of GFRC components.
Several projects were reported for building wall panels made of GFRC in UK and USA. GFRC has also been used for repair works and for industrial floors in USA.
Applications of Glass Fiber Reinforced Concrete
The glass fiber reinforced concrete usually finds applications in following construction works:
- Building renovation works
- Water and drainage works
- Bridge and tunnel lining panels
- Permanent formwork method of construction
- Architectural cladding
- Acoustic barriers and screens