What do they call the canvas / tarp like material used to make outdoor dividers at construction sites?

It is called 'silt fence' and is used to contain dirt/debris that would otherwise wash into surrounding waterways, storm drains, etc. It can be purchased at most lumber supply stores in rolls of 50 feet and has the stakes already attached. When used on construction sites the bottom is buried at least 6 inches deep to prevent debris from washing underneath. You may or may not want to do that in your yard. For leaf containment it shouldn't be required unless you are on a slope.

The leaves will decompose more quickly if they are broken up; I use a mulching mower to grind them as fine as I can before trying to compost them. Mix in an amount of soil roughly equal to the amount of leaves to further speed the process. Adding worms to the mixture helps, also.

Good luck and enjoy!

Not a good idea, cuts off ventilation. Get some corrugated plastic roofing cut it into one foot sections.

Punch three holes in the sides top middle bottom the same in each one, both edges, you can use a

paper punch for this just wiggle it back and forth. Lay all the panels on the ground then thread a good quality polyethylene string that will fit through the holes twice. Start at one end and thread the string through the first hole and tie it leaving a long piece then loop it through the next hole twice to lock it in place use a short piece of 2X4 between the panels for spacing. Loop the string at every edge to lock them in place. Do this on both edges then tie the two ends together and make a big circle, i use my lawn mower to mulch and collect the leaves so i can get ten times as much leaves in the circle.

When it's heaping full cover it with a piece of plastic to keep the rain and snow out.

Try looking at Walmart in the camping section. They have different size of tarps that should do the trick.. They are a heavy plastic with inter woven fibers for strength. They do have tie down grommets on the sides so you can tie them over something if you ever need a weather cover..

Does this stuff has holes allover and tends to be green or blue? if so its debris netting but if its clear plastic then its called monoflex. you can get it from most scaffolding firms cheaply

It's called debris safety netting