44142 The minimum pin diameter size for steel bar bending in accordance with

44142 the minimum pin diameter size for steel bar

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4.4.1.4.2 The minimum pin diameter size for steel bar bending in accordance with TTS 583:2002 is as shown in Table 4-6. Table 4-6 Recommended minimum pin size for bar bending Pin diameter Bar diameter "d" (mm) Steel grade 250 Steel grade 420 6 mm to 16 mm 3d (18mm to 48 mm) 4d (24 mm to 64 mm) 20 mm & 25 mm Not applicable 5d (100 mm & 125 mm) 32 mm & 40 mm Not applicable 7d (225 mm & 300 mm) 4.4.1.4.3 Steel reinforcement bars shall not be welded. 4.4.1.4.4 Steel reinforcement shall be free of loose mill scale (rust), and shall be properly tied together with mild steel tying wire. The whole assembly shall be positioned within the formwork with appropriately sized concrete spacers so that the correct concrete cover to the steel is maintained. The recommended concrete cover for different environmental conditions are given in Table 4-7 . 4.4.1.4.5 Vibrating of concrete shall be handled with caution. Concrete shall not be vibrated: a) by direct contact between the vibrating instrum ent and reinforcing bar; or b) by vibrating the formwork as this may displace the steel fixings.
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PCTTS 599: 20XX 69 Table 4-7 Recommended concrete cover Type of member Concrete cover (mm) Normal conditions Coastal environment Slabs 25 35 Beams 30 40 Columns 30 40 Foundations and other surfaces In contact with earth 75 95 Note: The recommended concrete cover for coastal environmental conditions is based on an increase of 25 % over that for normal conditions. 4.4.1.5 Placing concrete 4.4.1.5.1 Formwork shall be thoroughly cleaned to remove sawdust, bits of wood, wire and other debris before placing concrete in it. 4.4.1.5.2 Transporting the concrete over long distances (unless special equipment is used) shall be avoided to prevent segregation of its components. 4.4.1.5.3 All runways and routes between the mixer and the area where the concrete is to be used should be set up beforehand and kept clear, so that the placing of concrete can proceed smoothly without interruptions. 4.4.1.5.4 The poured concrete shall be compacted in the formwork by vibration or rodding, so that dense concrete is obtained. Where necessary, chutes shall be used to place concrete in restricted areas such as in column forms. 4.4.1.5.5 Where floor slabs or roof slabs cannot be poured in one operation, construction joints shall be used. Professional assistance shall be sought on the proper placing of the construction joints in suspended slabs. 4.4.1.6 Curing 4.4.1.6.1 The optimum concrete strength shall be obtained by proper curing. To achieve this, the curing concrete shall be kept moist, during the curing process, by wetting with water for four (4) days after it is poured. 4.4.1.6.2 Where proprietary curing compounds are used the manufacturer’s instructions shall be followed. 4.4.1.7 Stripping of formwork The side formwork of beams and columns may be removed from the fresh concrete after 24 hours, provided that provisions are made for proper curing. The bottom formwork and props for suspended beams and slabs shall remain in place for not less than 10 days.
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PCTTS 599: 20XX 70 4.4.2 Timber 4.4.2.1 Type of wood Walls, floors and roofs shall be constructed of structural timber. The timber should be sound, straight
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