I'm super interested in trying both strong vinegar and salt for weed control. I didn't see a discussion of some safety in regards to using strong acids, so I wanted to dredge up some pointers from my chemistry days.
1) pH is a logarithmic function of hydrogen ion (acid) concentration, so pH of whatever acid can be increased by 1 by adding 9x the water volume. So, pH 3 hydrochloric acid can be made pH 4 by making 1:10 solution. pH 5 would be 1:100 solution.
2) If at all possible, if diluting strong acids, mix the acid into the water, so any splash will be pre-diluted.
3) Although adding a base (e.g., baking soda) to an acid does neutralize it, it may also liberate heat in the process. Depending on strengths of both, this could add a thermal burn on top of a chemical burn. So, if you get a strong acid (or base) on your skin or in your eyes, best practice is to flush with copious water to rinse off and dilute to harmless levels. Baking soda is great for neutralizing acids on objects; I keep a box handy when working with the sulfuric acid in our battery bank.
4) As mentioned previously, goggles, rubber gloves, and impermeable apron are all advisable.
We had a large area of shale paths (from earthship excavation) between all our annual veg beds...within a short time they were colonised of course by soil repair plants aka weeds.
Having tried many remedies, in the end I took to encouraging the clovers to grow over the stone paths, with their dense, spreading habit. To achieve this I kept mulching and weeding out all other species.. after about one year it was looking hopeful, 2 years later we had a 2/3 coverage of clover on the gravels.
Apart from having to leave that garden!! I reckon it would have worked as a strategy from what I observed, and an alternative I was content with compared to the efforts and impacts of all the methods employed to keep stone paths weed free at that scale.
Cultivating connection between people and places for thrival and peace.
So reading through these posts I can see the issue is quite a bit more difficult that immediately apparent.
Personally, I have no problem whatsoever with weeds growing in my driveway gravel, I like that it holds the gravel together, cuts down on dust and I just prefer just about anything green to pure gravel. Mine gets mowed regularly and the weeds are lucky to get past an inch tall.
But if eliminating weeds is the goal, I can only think of 3 options.
Option #1 is of course the vinegar route as has already been discussed. I suspect this will require multiple rounds for weed elimination.
Option #2 would be the flame weeded. This is my preferred option, but it too will take repeated applications.
Option #3 would be to starve the weeds of something they need. I was thinking that maybe they could be starved of sunlight.
Many years ago I traveled Wisconsin where my wife’s uncle was having a family reunion. The lived on a lake and even had a boat dock and small beach area. The problem with the beach area was that all sorts of aquatic plants grew right in the best, sunny spots, but nothing grew by the dock which had a cover for a boat. Their approach was to occasionally spread 2,4 D pellets to inhibit the plant growth. So many aspects of this sounded revolting. I hated the idea of spreading poisons. Worse, these would be incredibly mobile, far worse than lawn applications (and that is bad enough!). Also I was just imagining that I would be swimming in diluted poison! Ick! Further, the results were only temporary.
My suggestion was to extend a tarp over the beach area when not in use (it was a small area and easily accomplished). Actually they were quite receptive. They could see that weeds were not growing in shady areas. I still don’t know if they took this approach, but would it be at all possible to deny the troublesome plants light? Maybe shade along with other controls could work?