Very odd question but whats the cheapest material that can be used to create a thin raised edge at the end of concrete blocks? . We have a raised bed garden and often find that when it rains heavily, a lot of dirt, water will flow out of the bed into the pathway. If we could raise the edge of the concrete block that borders our raised bed ever so slightly with a dollop of cement or something, it would be helpful in keeping the water and soil in when it rains.
It does not have to look pretty at all. Something thats cheap and will hold up relatively well but can be taken down later on with a chisel or something should we decide to salvage the concrete bricks or remove the add on edge when we move.
You should post some picture(s) of what it is exactly you want to add this raised edge to, that would help a lot with the answers you will get @ahappycamper.
But by the sounds of it, it seems what the real problem is is that the raised garden doesn’t have sufficient drainage from its bottom. Raising the top edge a little bit will only delay most downpours from flowing over its new raised edge you want to install but will still happen, just maybe not as often or as quickly as happens now.
Definitely a picture of your raised bed would help.
Is it a straight border or a curved border?
Was it raised as in a retaining wall? Or did you just put a course of bricks like a curb?
What is running into your path? Is the rain washing soil into your path, or is floating mulch spilling over the edge? Is the runoff infiltration of the raised bed too slow?
You can raise the border, or you can divert the flow. It all depends on what’s going on.
You mentioned a thin edge and the cheapest material, and concrete mix. Doubtful it will last, be cost effective, and removable. Without knowing more, your best bet may be those thin plastic edger that they sell at home centers I think they come in rolls, bendable, very thin, and in different colors. Buy one of those and tap that in on the inside of the existing bricks. Then observe what happens. If it solve the problem fine, if not you can easily remove it and go with plan B or plan C.