Testing of Grout 1

[xkybb]

Hello!

In my country, grout for pile is tested to ensure compliance with the following criteria:
1. 28 day Compressive Strength
2. Flow Cone Efflux Time > 15s
3. Free Expansion < 10% in total
4. Bleeding < 2% in first 3 hours; < 4% in total and 24 hour reaborption

I understood that the control on bleeding is important to avoid excessive upflow of water leading to void, and 28 days strength is important for loading transfer.

However, what are the purpose/intention for limiting the free expansion and flow cone efflux time of gorut?

Can anyone explain?

 

[xkybb]

Also
In case of construction of socketed steel h-piles surround by grout, what should we do if:
1. The bleeding test fail?
2. The free expansion test fail?

 

[PEinc]

"However, what are the purpose/intention for limiting the free expansion and flow cone efflux time of grout?"

Flow cone efflux time is a quick and easy way to field-check the proportions of the grout mix. When compared to the flow time for a properly mixed grout, a different flow time reading in the field will indicate that the mix is too stiff or too loose, indicating incorrect ingredient proportions of water or cement. Research Mud Balance.

https://en.wikipedia.org/wiki/Mud_balance

http://www.PeirceEngineering.com

 

[PEinc]

The mud balance is used for grout with fine aggregate or no aggregate, usually for ground anchor grout. Drill holes for soldier piles are often filled with low strength, flowable fill or lean concrete. Sometimes, higher strength concrete is used around the toe of the soldier piles, below subgrade. You don't want strong concrete to interfere with installing lagging boards above subgrade.

http://www.PeirceEngineering.com

 

[cvg]

it would be rare for a grout to expand more than 10%. cellular grout might expand more than that, but you are not using cellular grout for piles are you? Most non-shrink grouts expand less than 3%. have you ever failed an expansion test?

 

[PEinc]

xkybb needs to describe the type of grout that is proposed or specified for use with the soldier piles. I can't imagine anyone using non-shrink grout for filling soldier pile drill holes. Tieback anchor grout, soil nail grout, and flowable fill for soldier piles shrink, not expand.

http://www.PeirceEngineering.com

 

[xkybb]

Thanks for the replies.

Non-shrink grout was used for my project. The grout was mixed with water, cement and admixture (Cebex 100).

The grout has never failed in an expansion test, while I would want to know the purpose of having such a limit on the free expansion % in the Contract.

Also, what is the point for limiting the grout fluidity (flow coen time > 15s)?

 

[xkybb]

Further information
The pile is a bored pile with a 610mm permanent steel casing, inserted with H piles and the grout is only used to fill the void between the pile shaft and the steel H pile.

 

[cvg]

http://www.fosroc.com/product/show/cebex-100[/URL]]Cebex 100 is supplied as a powder admixture. The material is a combination of a plasticising agent and a gas producing expansion medium. The plasticising agent allows the use of a reduced water/cement ratio with consequent increased strengths and durability. The expansive medium counteracts the natural settlement and plastic shrinkage of the grout and aids stability and cohesion.

so limiting the expansion will limit the amount of gas produced, reducing the voids and producing a more dense material. A large expansion should not be required.

 

[Amilcar_Q]

Hi,

Expansion is important because you don't want excessive forces inside the beam, think like this: when you have water inside the pores of concrete and you freeze that, the ice increases volume and cracks the concrete. And undesirable increase in volume inside a beam can crack the beam.

The grout fluidity have relevance on larger spams, and also the ambient temperature plays a good part in the process of injection. If the grout fluidity y near 15s a you have a long beam, you may risk clogging the duct because as the grout flows in the vain, the grout gets more and more dense. that's why you have to measure the fluidity at the beginning and at the end of the injection, and make adjustments if needed.