First off, no ordinary grout is truly colloidal - even in the best mixed batches the cement particles do settle. "Colloidal" mixers simply do a better job of dispersing clumps, separating air, and wetting individual grains.
Obermann mixers are not "colloidal" but can produce perfectly good...
I assumed the OP was familiar with concrete work and was describing the cracking as outside of what's expected for normal shrinkage. Perhaps this was not a good assumption.
I'm still unclear on what's existing. What is there right now? A wall? A slope? Something else?
If you are installing this drilled shaft and loading it laterally at subgrade you have a condition just like a soldier pile toe, which means the shaft will resist the load by developing passive...
Can you post a sketch? It's not very clear what the existing conditions are, what the original design is, and what you are proposing to redesign (and why).
I think the OP is talking about a soldier pile with the toe in soil, in which case it's a waste to use any structural concrete. Also, I'm unclear on why a pile with structural concrete in the toe would provide more overturning resistance than one with flowable fill.
Also, pouring structural...
FHWA has manuals on anchored soldier pile & lagging walls as well as soil nail walls (Geotechnical Engineering Circulars #4 & #7).
For this hybrid system, I would think the facing would have to be very thick and much more heavily reinforced than a traditional soil nail wall. I'm picturing...
How far behind the wall are the deck footings, and how deep are those footings? The footings ought to go at least 3ft deep, so for a retaining wall that short, I doubt the deck is imparting any load to it.