12. GLASS REINFORCED CONCRETE

Description

Glass Reinforced Concrete (GRC) is a composite material consisting of a portland cement and sand mortar, reinforced with alkali-resistant glass fibres. The GRC may contain additional filler materials and admixtures. The final properties of GRC depend on a wide range of variables such as mix materials and formulation, manufacture, fibre product type, length & orientation and admixtures used.

GRC is a composite material which combines the high compressive strength properties of cement mortars with significantly increased impact, flexural and tensile strength imparted by the fibre reforcement. GRC does not contain asbestos, has good chemical resistance and will not rot or corrode. GRC is made of inorganic materials and will not burn, has negligible smoke emission and offers good fire resistance. Products of relatively thin cross section can be made, giving a low component weight which may allow savings in handling, storage, transportation, installation and in the supporting building frame.

The potential for the use of glass reinforced concrete systems was recognised during the early development work on glass fibre reinforced plastics carried out in the 1940s. Following the successful
development of AR (alkali resistant) glass fibres in the late 1960s, test programmes were undertaken to determine the properties of portland cement and AR glass
fibre composites. GRC is also used for furniture, cladding and as permanent formwork.

Typical products made using the spray process include architectural cladding panels, agricultural
components, tanks, facade elements, ducting and formwork.

GRC panels, through the application of finish shape, color, or texture, contribute to the architectural form and finished effect of a structure’s facade. Design flexibility in surface appearance is possible by incorporating various cements, coarse aggregates, sands, and pigments into the face mix. Natural stone products may be used as a veneer finish if special design requirements are met. Alternatively, panels may be painted or stained to achieve the required colors.

MATERIALS :
1. Portland cement type 1
2. Silica sand with fine gradation and silica content > 96%
3. Glass fiber with alkali resistant type and at least 16% zirconia content
4. Clean water with no pH
5. Admixtures such as polymers, superplasticizers and color pigments

PHYSICAL PROPERTIES :
1. Compressive strength 500 – 800 ksc.
2. Tensile strength 80 – 120 ksc.
3. Flexural strength 180 – 300 ksc.
4. Punching shear strength 250 – 350 ksc.
5. In-plane shear strength 70 – 120 ksc.
6. Interlaminar shear strength 20 – 40 ksc.
7. Dry bulk density 1.8 – 2.1 ton/m.
8. Water absorption 8 – 13 %
9. Apparent porosity 16 – 25 %
10. Fire resistant up to 4 hours.

REFERENCE :
The International Glass Fiber Reinforced Concrete Association, UK.