This is a common problem. We have been getting a lot of calls from all over New England where homeowners have a gap between a concrete walkway and a stone or block foundation. They try to put caulking or concrete skirts but the gap keeps reappearing.
This is a problem because when they pour a concrete walkway, even if they do a great job pouring it right near the foundation, there is water in the concrete. The water evaporates which causes a gap. Concrete expands and contracts with the temperature. This also happens with an asphalt walkway. It doesn’t bond with concrete, block or stone; and the gap remains.
The reason we want to fix it is so that water doesn’t get in there, freeze and cause the gap to get bigger. We have talked with chemists to fix it, and have come up with a product that will go into the seam. First, we put sand in the seam and then we put the material that has elasticity into the seam to bond with the masonry material, asphalt, concrete, and to the foundation wall. It gives, so it can move. Them we put a special skirt over it to further protect the area so that water can't get in.