We are manufacturing PSC sleepers with short bench system at our Chamagram factory.

Moulds and Benches :
Mould and benches being used are of steel and are rigid in construction so as to prevent any distortion during casting of sleepers. The moulds do not allow any appreciable leakages for cement mortar in casting. The holes in the end plates are accurately drilled for correct placement of pre stressing wires.

Stretching of Wires :
The pre stressing wire is stretched collectively through hydraulic jacks. The tensioning forces are as per sleeper drawing. The final force is adopted, duly considering the frictional losses while stretching is approved by the clients. However, the stretching force does not exceed 75% of the minimum specified UTS of the wire under any case. The pre-tensioning force in the wire is applied through tensioning device equipped with automatic load cut off unit along with measuring gauge. The final force is also verified/cross checked by measuring the extension of the wire.

Mixing and Consolidation of Concrete :
Manufacture of sleepers is done under a shed.
Batching of different ingredients is done by weight (after free water content adjustment) only for which a mechanized weigh batcher is used for weighing aggregates and cement.

  1. High speed pan mixer is used for mixing concrete. Concreting commences with in two hours of stressing of wires.
  2. Concrete is thoroughly mixed and consolidated by means of vibrators of at least 9,000 revolutions per minute or (rpm).
  3. Freshly cast sleepers are protected during the first stage of hardening from adverse weather conditions.

DE tensioning of Wires :
The anchor system provides a device for gradual de tensioning of the wires. Back pulling of wires for releasing any wedges is not done. De tensioning of wire is undertaken only after the concrete has attained a compressive strength of 50 N/sq.m.

Curing :

  1. The initial curing is done by Steam till the concrete attains a compressive strength of 50 N/sq.m. Pre steaming period is not less than the initial setting time of the cement. Steam curing cycle has to have the prior approval of the client.
  2. After dimensioning, the sleepers are cured for further period of fourteen days for Straight-line sleepers and twenty-eight days for Turnout sleepers by submerging in water tanks.

Loading :
The sleepers are loaded into wagon / trucks mechanically with the assistance of gantry cranes.

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