SECONDARY GROUTING OF COLUMNS STRUCTURE AND EQUIPMENT FOUNDATIONS FOR THERMAL POWER PLANT

We have covered the topic of Bolting in structures and one more important activity to be done to

all columns , equipment foundations ( static /rotating)  is secondary Grouting . The process of 

doing the same is given below. 

-The surface of the foundation shall be dressed up to required level before placement of column.

- Top 25 mm  /loose concrete should be chipped of  and cleaned.

- If necessary grove is to be made on the foundation for placing packer plate.

-  The grouting cement shall have high strength having minimum compressive strength.

-  The value is 50 to 60 N/mm2 at 28 days.

- The grout shall be  chloride free, cement based ,non-metallic , free flowing Grout.

- The Grout shall have good flow ability even at very low water/ grout powder ratio.

- The Grout shall have characteristics of controlled expansion to be able to occupy 

   its original volume to fill the voids and to compensate for shrinkage.

- Grout shall be of pre-mix variety so that only water needs to be added before use. 

- After the base has been prepared, its alignment and level has been checked and approved

  and before actually placing the grout, a low dam shall be set around the base at a distance

  that will permit pouring and manipulation of the grout. The height of such dam shall be

  

  at least 25mm above the bottom of the base. Suitable size and number of chains shall

  be introduced under the base before placing the grout, so that such chains can be moved

  back & forth to push the grout into every part of the space under the base.

- The top surface pocket of the bolts etc was cleaned with water .

- The surface was then cleaned with compressed air to remove any presence of water in the pocket.

- The grout shall be poured either through grout holes if provided or shall be poured at

 one side or at two adjacent sides to make the grout move in a solid mass under the base

 and out in the opposite side. Pouring shall be continued until the entire space below

 the base is thoroughly filled and the grout stands at least 25 mm higher all around than

 the bottom of the base. Enough care should be taken to avoid any air or water pockets

 beneath the bases.

- There are few suppliers in INDIA who are supplying ready mix concrete in 25 kgs bag.

- The suppliers are  FOSROC ( CONBEXTRA GP 1 OR GP 2) , ACC ( SIKKA ) 

   PIDILITE ( PAGEL CEMENT).

- It is all time better for grouting critical area manufacturer's representative should be 

  present at site during grouting and taking sample for cube test.

- The columns is to be loaded before grouting so that there is no deviation from initial data.

Above picture show the secondary Grouting of Turbine pedestal . Form work is seen in the picture .

Already grouting has been completed.

Concrete pouring through mechanical mixture machine under progress.

Inspection on  grouting is still under progress. Types of RMC used (Pagel)

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