Tieback grout 2

[pelelo]

Hello,

I have a question about a deep excavation project I am working on and tiebacks, beams and laggings will be necessary.

For grouting the tiebacks, I have noticed different specs require different UCS for the tieback grout.

I was wondering what is the problem or the risk of grouting tiebacks for example using 3000 psi grout vs 4000 psi grout?.

To my knowledge this is more a construction issue than a design issue, am I right?.

I don't think the change in UCS of the grout will change the bond strength of that grout vs the soil or rock.

Please let me know,

Thanks

 

[ATSE]

Keep in mind that f'c is used as a proxy for other concrete properties, like shrinkage and permeability.

 

[Lomarandil]

I'm not very familiar with grouted soil anchors, but for grouted concrete anchors there is typically a (non-linear) proportional relationship between grout compressive strength and bond strength.

 

[PEinc]

Grout for tiebacks, tiedowns, and micropiles is almost universally specified as a neat mix of 5 gallons of water per 94# bag of Portland cement. This mix usually produces a minimum unconfined compressive strength of 5,000 psi. If the tieback anchor passes its proof or performance test, the grout is sufficiently strong despite what any grout tests may indicate. There may be other threads on ET that discuss tieback grout. The compressive strength of the grout does not enter into the design of the ground anchors but does affect the design of micropiles.

http://www.PeirceEngineering.com

 

[pelelo]

ok Thanks a lot for your comments!.