Adhesive/Cementitious Grout

[dik]

The following is from an eMail sent to a grout supplier...

Can anyone suggest a product?

We have a project as follows. Existing concrete is sound and good quality and is approximately 40 years old. This will be cored with a 6" dia core drill for a length of approximately 20' to 25'.

We need to anchor a high strength 1-3/4" dia Dywidag threadbar into the bottom of the hole using a cementitious grout. Temperature of the concrete will be approximately 0 degC to -5 degC.

The threadbar will be tensioned to a service load of approximately 320,000 lbs. The grout will have to bond to the freshly cut concrete surface and will have to develop suitable strength within two days. Service loading will be sustained over several decades (>50 years). Quality control and quality assurance will be first rate. The anchorage development length can be several feet.

We are currently entertaining the use of Sikadur VPC. Is this product suitable? Is there a better product that you can recommend?

thanks, Dik

 

[ishvaaag]

Mechanically it seems it is a valid choice. However, the technical info seems to indicate main use is for overlays, and placement recommendations asks for particular ventilation requirements to be met with some difficulty in a long shaft without maybe inducing blowholes in the set material. Has it been suggested by Sika itself? If no better ask their direct advice, or other specialty house.

 

[dik]

thanks ishvaaag... I'm waiting to hear from them... if used for overlays, then the bond strength should be there... the loads are 'big' and 'real'... I was wondering if anyone in the forum was used to 'gluing' down post-tensioning rod...

Dik

 

[Ron]

dik...your shear bond stress is only about 70 psi. The Sikadur material should handle that; however, placement of any catalyzed epoxy to that depth will be a challenge.

 

[dik]

I was thinking of 'bagging it', breaking the bag and extraction or of pumping it (like tremmie, but no water). It will have a thickness of several feet to minimise the shear-bond due to the early stressing age, I suspect it will work, the critical issue is the temperature and the high load at a matter of a couple of days... schedule does not permit a longer period of time before stressing. The loading is critical and sustained, failure can be catastrophic. Want to avoid similar problems to 'Big Dig'.

Dik

 

[BAretired]

It is a little outside my area of experience, but don't the Dywidag people have a suitable anchor?

http://www.dywidag-systems.com/products/geotechnic/dywidag-bar-anchors/anchor-types.html

BA

 

[dik]

I've got a posting in to them also... the initial one I had from them was a cementitious flyash type of material, and I was looking for something with a little more 'stick'...

Dik