I am planning to lay down edging around the lawn in my garden - leaving about 750 mm wide flower beds along the fence. All in all, I need to lay down about 23 meters of edging slabs - it will be these ones:
The idea is to dig a shallow "trench", pour a base of cement mixture to level the bottom, then set the edging blocks and add a bit more cement mixture on the sides to "fix" them to the base. Finally, add back some soil to cover all the cement. There will be about 10 cm of the blocks visible above the ground.
My question is, given the length of 23 meters (about 75 feet) and the width of the blocks of 5 cm (about 2 inches), how much cement/sand do I need to buy?