4.10　Secondary Grouting and Curing

4.10.1　Before the secondary grouting of turbo-generator unit foundation，the following work shall be completed and records be made unless there are special requirements from the manufacturer:

1　Installation of main equipment of turbine has been completed.

2　Adjustment of generator and exciter magnetic center and air gap has been completed.

3　Adjustment of radial clearance of water outlet support water baffle generator with water-cooled rotor has been completed.

4　Final centering of shaft system has been completed.

5　Laying of pipes，cable and instrument conduits and lines through the secondary grouting layer has been completed，and dedicated sleeves have been placed.

6　All foundation pad blocks have been fixed by spot welding.

4.10.2　The following preparatory work shall be done before secondary grouting of foundation:

1　The sliding surfaces of insulated plate and soleplate of generator bearing pedestals and electrical equipment below the generator shall be properly protected against contamination in secondary grouting.

2　The foundation concrete surface shall be cleaned by blowing，and be free of sundries，paint or oily dirt.The concrete surface shall be wetted for 24h and over.

3　The surface of soleplate for contact with secondary grouting shall be cleaned，and be free of paint or oily dirt.

4　The inside of anchor bolt holes shall be cleaned，the anchor bolt base plates shall be in good contact with foundation concrete，to ensure no leakage during concrete casting.

5　Location of secondary grouting must not hinder thermal expansion of turbine and piping，nor block the soleplate oil injection or drain holes.

6　For nuts of anchor bolts inside secondary grouting layer，sleeves shall be fitted for nuts and operation space for tightening or loosening the nut shall be provided.

7　Formwork for secondary grouting shall be firmly mounted and any seam be eliminated；the top elevation of formwork shall be higher than the upper surface of equipment base plate.

4.10.3　When foundation secondary grouting is performed by civil works personnel，erection personnel shall provide close cooperation.

4.10.4　The secondary grouting and curing for foundation of turbo-generator units shall comply with the followingprovisionsinadditiontothoserequiredbymanufacturerandspecifiedinPart1"Civil works"of this specification:

1　Grouting materials with micro expansion or non shrinking shall be used.

2　The inside of soleplate shall be densely grouted，and on the periphery，it shall be ensured that the grouting level is above the upper surface of base plate.

3　The secondary grouting for the foundation of turbine，generator and exciter should be completed in one time.Soleplates for interconnected structures and soleplate to be linked together after secondary grouting must not be grouted separately.

4　Any mortar splashed onto equipment and bolt surfaces during grouting shall be cleaned in time.

5　For grouting，concrete test blocks shall be made as specified and be cured under the same conditions as secondary grouting layer，strength test shall be made at required time and report shall be prepared.

6　After grouting，the foundation shall be cured as required，and the ambient temperature shall be kept between 5℃-35℃during the first 3 days of curing.

7　Before the concrete strength of foundation secondary grouting layer reaches 50%of design strength，no heavy part assembling and disassembling or impacting work is allowed on the unit；retightening of anchor bolts or start of unit is not allowed before it reaches 80%of design strength.

4.10.5　For secondary grouting of foundation concrete，the construction process shall be put under strict control，after removing formwork at the expiration of curing period，the appearance and internal quality shall comply with design requirements，and be jointly inspected and signed by relevant personnel.