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Unformatted text preview: Cover - The minimum clear cover for reinforcement in pipes and collars shall be as given below: to 140/125. An effective means shall be provided for maintaining the reinforcement in position and for ensuring correct cover during manufacture of the unit. Spacers for this purpose shall be of rustproof material or of steel protected against corrosion. Minimum Clear Cover 6. MANUFACTURE mm 6.1 General - a) Barrel thickness The methods of manufacture shall be such that the form and dimensions of the finished pipe are accurate within the limits specified in this standard. The surfaces and edges of the pipes shall be well defined and true, and their ends shall be square with the longitudinal axis. 1) LJp to and including 25 mm 6 2) Over 25 mm and up to and 8 3) Over 30 mm and up to and including 75 mm 10 6.2 Concrete Mixiog mechanical mixer. 4) Over 75 mm 15 b) At spigot steps 4 c) At end of longitudinals 5 6.2.1 Mixing shall be continued until there is a uniform distribution of the materials and the mass is uniform in colour and consistency, but in no cast shall the mixing be done for less than two minutes. including 30 mm I9 Concrete shall be mixed in *a IS : 458 - 1988 62.2 Water-cement ratio shall be less than 0’5. and the pipes conform to the requirements of this specification. 6.2.3 The concrete shall be placed before setting has commenced. It should be ensured that the concrete is not dropped freely so as to cause segregation. The concrete shall be consolidated by spinning, vibrating, spinning combined with vibrations, or other appropriate mechanical means. 6.4.3 The manufacturer may, at his option, combine the methods described in 6.4.1 and 6.4.2 as long as the specified strength is attained. 7. DIMENSIONS 7.1 Pipes - The internal diameter, wall thickness, length and thickness of collar of pipes, the minimum reinforcements and strength test requirements for different classes of pipes ( see 3.1 >, shall be as specified in Tables 1 to 7. The manufacturer shall inform the purchaser of the effective length of spigot and socket, and flush jointed pipes that he is able to supply. For collar jointed pipes, effective length shall be 2 m up to 250 mm nominal diameter pipes and 2’5, 3’0, 3’5 or 4’0 m for pipes above 250 mm nominal diameter. 6.3 Reinforcement Cages - Reinforcement cages for pipes shall extend throughout the pipe barrel. The cages shall consist of spirals or rings and straights of hard-drawn steel wire or mild steel rod and may be circular. Circular cages and longitudinal reinforcement shall be placed symmetrically with respect to the thickness of the pipe wall. The spirals shall end in a complete ring at both the ends of a pipe. 6.3.1 Pipes having barrel thickness above 75 mm shall have double reinforcement cage and the amount of steel in the outer cage shall be 75 percent of the mass of the inner cage whilst the total shall conform to the requirements specified in the relevant tables of this standard. The total longitudinal steel per pipe shal...
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