sinking sidewalk + gap @ foundation

[mr.roboto]

I've got a decent 2 year old sidewalk next to my foundation wall that's sinking or just settling into place. It's opened up a deep gap that's less than 1/2" wide where it meets the foundation wall. Water usually flows away from the gap, but it can get in there + with freeze+thaw I think the gap will only get bigger.
How can/should I fill the gap ?
Sand mix concrete delivered through a grout bag :?:
hydraulic cement :?:
that liquid rubber concrete patch :?:

[Rich]

I would probably start with hydraulic mortar to fill in the largest gaps and then go over top of it with either flashing and/or a liquid waterproofing.

[mr.roboto]

RICH -
I assume that by flashing you mean a little sheet metal hat, but what type of liquid waterproofing ?
Vinyl concrete crack filler or caulk or a concrete sealer of sorts ?

Thanks Again - - - Rob

[Rich]

There is a product I'll be using called hydrotex or hydro tech something like that anyway - I haven't received the specification sheet yet. The installer says it's saved his bacon a couple times.. it's a liquid applied waterproofing. Here it is http://www.hydrotechusa.com/START.HTM

[southern eliteCrete]

if this is as i understand it, insert some closed cell backer rod & caulk the opening with dow-corning silicone or other suitable material,,, be certain to 'prep' the sidewalls properly (slightly abrade & CLEAN WELL!!!),,, set the backer rod to a depth that will allow proper dimension configuration of the material,,, 'tool' with a wet teaspoon unless you have a pro's spatula