This standard outlines the specifications for corrugated translucent sheets composed of thermosetting polyester resin reinforced with glass fibres, intended mainly for roofing. It defines dimensional criteria, mechanical properties, light transmission capabilities, and durability features compatible with profiles of galvanized steel, asbestos cement, and aluminium roofing materials. It serves as a crucial reference for manufacturers, engineers, and architects ensuring structural reliability and controlled light diffusion within temperatures from -20°C to +60°C.
Overview
This standard outlines the specifications for corrugated translucent sheets composed of thermosetting polyester resin reinforced with glass fibres, intended mainly for roofing. It defines dimensional criteria, mechanical properties, light transmission capabilities, and durability features compatible with profiles of galvanized steel, asbestos cement, and aluminium roofing materials. It serves as a crucial reference for manufacturers, engineers, and architects ensuring structural reliability and controlled light diffusion within temperatures from -20°C to +60°C.
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Contents
Structure
Frequently Asked
IS 12866 establishes dimensions and tolerance limits for glass fibre reinforced translucent corrugated sheets aligned with profiles from IS 277 (galvanized steel), IS 459 (asbestos cement), and IS 1254 (aluminium). Key dimensional parameters include corrugation depth, pitch, overall width, effective width, minimum thickness, and sheet length. Length tolerances are set at ±0.5% of the sheet length, with minimum thickness tolerance at +0.15 mm. These specifications ensure compatibility with roofing profiles and consistent product performance.
The glass fibre content is determined by weighing the sample in a pre-weighed crucible, then gradually heating it in a furnace up to 565 ± 28°C until a constant weight is achieved, followed by cooling and re-weighing. The percentage of glass fibre is calculated from the weight difference before and after ignition. According to the standard, the minimum glass fibre content by weight in the laminate must be at least 30%, ensuring adequate reinforcement for strength and durability.
The standard mandates two primary mechanical tests: the load deflection test and the Barcol hardness test. The load deflection test applies to corrugated and curved flat sheets of specified thickness, requiring no rupture and limiting deflection to a maximum of 15 mm under prescribed loads. The Barcol hardness test measures surface hardness, with the condition that hardness increase after testing does not exceed 30% of the initial value. These tests verify the sheets' structural integrity and surface durability.
Light diffusion is classified based on the Gradient Constant (G), measured using a slit diffusion photometer as per Annex F. The classification ranges from Class I (clear) with G above 0.80, to Class IV (very heavily diffusing) with G below 0.10. This categorization helps in selecting sheets suitable for varying translucency and light scattering requirements in architectural and roofing applications.
The recommended operational temperature range for these translucent glass fibre reinforced sheets is from a minimum of -20°C up to a maximum of +60°C. Maintaining usage within this range ensures retention of their mechanical properties and optical performance without degradation.
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