It seemed to be crucial to make the glass itself alkali resistant and at the

It seemed to be crucial to make the glass itself

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It seemed to be crucial to make the glass itself alkali resistant, and at the end of the 1960’s a suitable glass formulation was identified containing zirconia (ZrO 2 ). After numerous trials the zirconia content was optimised at approximately 17%. In the 1970’s the technology was developed to produce AR-glassfibres from this glass formulation, and the Glassfibre Reinforced Concrete industry was born. For almost 50 years of ongoing development, the industry now presents better quality glass fibres with a wider variety of sizing, new pozzolans to enhance the overall GFRC properties, low alkali cement to reduce the attack on the fibres, improved and diversified equipment, and more manufacturing methods. During this time, the market has witnessed continual growth in the volumes and the range of products manufactured. Today GFRC has become one of the most versatile building material available to architects and engineers. 2.2. GFRC components GFRC is a composite material, which combines the high compressive strength of cement mortars with significantly increased impact, flexural and tensile strengths obtained by the glass fibre reinforcement. According to the particular product and the engineering design, GFRC formulation materials are normally involved with the following: Alkali Resistant (AR) Glass Fibre Products AR glassfibre is specially formulated to have a high degree of resistance to alkali attack and high durability in cement. Laboratory testing shows that at least 16% zirconia content is required for adequate alkali resistance. AR glassfibres are available in roving, chopped strand, net and mat forms. The use of roving for hand spray including auto spray and chopped strands for premix are most common, with scrim being used in areas of high stress concentrations and mat for the similar application although more successful in floor screeding. Cement Ordinary Portland Cement (OPC), Rapid hardening Portland Cement (RHPC), Calcium Sulphoaluminate Cement (CSA) and White Portland Cement are the most commonly used cements. They should conform to the relevant National or International Standards. CSA cement is widely used in the Far East due to its low alkalinity and rapid hardening properties, which consequently reduces
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WMCAUS 2018 IOP Conf. Series: Materials Science and Engineering 471 (2019) 082054 IOP Publishing doi:10.1088/1757-899X/471/8/082054 3 the corrosion of fibres and speeds up the mould turnover. White Portland Cement is used in GFRC where a white or light coloured finish is required. Sand Properly graded silica sand is recommended. The particle shape is preferably round or irregular but having a smooth surface without honeycombing. For spray GFRC, the maximum particle size is generally limited to 1.2 mm; for premix GFRC, the maximum particle size may be 2.4 mm. Sand other than silica sands may be used but the producer should provide evidence of their suitability.
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  • Fall '19
  • GFRC

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