nader666
Structural
- Mar 7, 2013
- 21
Hi everyone,
I am using shotcrete mix to repair slab ceiling and walls of wastewater tank.
I have proposed the following scope of work for the tanks repair:
SCOPE OF WORK
1.Remove of deteriorated concrete cover throughout the tank ceiling and upper section of the walls up to at least 1 foot
below lowest liquid level.
2.Remove any loose concrete /cracked concrete around severely corroded rebars to provide at least 1” clearance around and
under the rebar, then sandblast the ceiling /walls rebars to the clean white steel.
3.Shotcrete wire mesh should be hot dipped galvanized 4”x 4”x D2.9 x D2.9. to be placed on ½”damiter galvanized expansion
hook bolts every 18” both way. Distance between existing sound concrete surface and wire mesh shall not be less than
1”. Layer of shotcrete below the wire mesh must be not less than two inches. Wire mesh should be lapped at least 2
times the spacing on each direction.
4.The wire mesh must be secured to the hook anchors by using 16 gage tie wire.
5.Xypex Admix C – 1000 NF to be added to the shotcrete mix ( at least 1.25% by weight of
cementations content).
6.The 28 days compression strength of the shotcrete mix must be at least 5000 psi , minimum cement factor is 700 Ib/
yd3, Silica Fume additive ( 5% weight of wet material ) and steel fiber ( 2.5% weight of wet material ).
One of the bidders has claimed that the use of steel fiber is a problem. Fibers, whether steel or poly, should not be used with fixed reinforcement: the fibers tend to bridge around the fixed steel, preventing proper encasement.
Does anyone has ever used stel fiber/wire mesh combination or know that it should not be used?
Thank You
