lawn

You will find it a long tedious job, getting sand into fork holes, I would just leave them open. If you want to spike your lawn you need a hollow tyne spike roller which will make big holes in which you can brush grit or sharp sand out of the way of your mower.

Be careful using builders' sand - in case it has salt in it. That is the best way to kill plants! You need to find out before you use it. I wouldn't risk it, myself.

i would not use builders sand, you should get it from garden centre, i spiked my lawn last November with garden fork and brushed two bags of sand into holes, it is now all the better for it, nice and dry and getting ready for a light trim ! its hard work but you will feel fitter for it !!!
Vauxhall