Debbie from East York, Ontario has a problem with a basement leak that apparently is caused by a crack between the sidewalk and the wall. Her contractor patched it last year, but it leaked again.
If there is any movement of the sidewalk, from frost or just swelling and or shrinking clay, then no rigid patch will hold between the sidewalk and the house. If you really want to simply seal this joint, use Polyurethane sealant, most easily found as PL Polyurethane by LePage in a caulking tube. You can get it in limestone colour to match the concrete. Really clean both surfaces and remove anything that is loose. At this stuff never dries, it cures to a very flexible rubber that will stay elastic for 50 years.
But that may not solve your problem, if the runoff from this area simply goes to the end of the sidewalk and then down into the soil under the sidewalk and on into the basement. You could of course dig everything up and waterproof the basement wall, but that is very expensive and rarely necessary.
Back to basics. If we can get the water away from the area, we don't need to waterproof it. Make sure that the roof has rain gutters to minimise the water coming off the roof. Make sure the downspouts go far away from the problem area and flow even further away, not back to the house. It may be that the concrete sidewalk itself slopes in the wrong direction. This can be changed with slab jacking, where they pump clay under the sidewalk to change it's slope away from the house. Look up "Slab Jacking" in the Keyword section for more details. If you are trying to manipulate large patio blocks, check out "Slab Setters" to make the job easier.
I hate waterproofing a wall from the inside. If you have a lake on the outside, it will just eventually find another crack. Let's get rid of the water by good landscaping.