9 step of Grouting process for post tensioned concrete girder and segments.

IMAGE CREDIT : MIDAS

After stressing all the cables, grouting should taken up at the earliest. Strands are cut to minimum length keeping about one inch from the bearing plate. The grout cap is to be fitted prior to the grouting operation.

9 Steps of Grouting process for post tensioned concrete girder and segments.

STEP-1 Remove loose material / dirt etc. from cable duct by passing water through the threaded grout hole of the tube unit. A ball valve and a threaded pipe is fitted to this grout hole of the tube unit.

STEP-2 After flushing the duct with water and it has to be ensured that clean water comes out from the other end. Compressed air may also be used to remove Traces of water into the duct.

STEP-3 Ball valves should be fixed at inlet location and is connected to the grouting Pump with a high pressure hosepipe.

STEP-4 Dual piston electrically operated grouting pump developing a pressure of Minimum 10 kg/cm2 and a delivery of 20 liters per minute will be used.

STEP-5 Grout should be made in a drum of 250 ltrs capacity and a grout agitated by grout agitator to make colloidal mix. First water should be added to the drum.  Cement bags to be emptied in the drum. This mix should be agitated by keeping the electrical agitator on the top of the drum.

An non shrink additive generally FOSROC Conbex - 100 or equivalent is used in proportionate of 0.5% by weight of cement.  

The water cement ratio of the mix is between 0.4 to 0.45. The temperature of the grout also should be controlled in case of hot atmosphere by using ice water.  The agitated grout should be passed to the small drum by sieving to remove lumps or minor unwanted particles.

STEP-6 The properties of grout like compression strength is to be checked on a 100mm cube. The minimum strength at days is to be 17 Mpa.

STEP-7 The grout shall be made just before the grouting operation and shall be kept agitated unit it is pumped. Grout once made shall be consumed with in 30-45 minutes.

STEP-8 Grouting shall be carried out in one continuous operation. The grout should be pumped from one end of the girder. The grout should be allowed to pass through the other end with the same consistency before closing the grout hole opening. The bolt fitted to the grout cap also should be loosened or refitted on the other end to ensure air be expelled out.

STEP-9 After a consistent grout starts coming out of the outlet, it shall be closed and the pressure maintained at 5 Kg/cm2 for at least 30 seconds.  Once the grouting operation is complete ,the inlet ball valve should be closed. The grout in the pump line should be by passed to remove the pressure at the pump end. Shift the pump for next grouting operation.

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