[jrko]

I can lay my hands on huge quantities of chalk and I was wondering if it might be useful.

I will be building a central path and a lean to greenhouse both of which need some form of hard standing material on the cheap - or free ideally

I've seen chalk used in cattle sheds, all be it heavily compacted, so it can withstand abuse & load. It is also water permeable.

I thought for the greenhouse it would reflect light and as a solid mass have some thermal storage properties as well.

Any thoughts?

[JayG]

Assuming it is chalk (calcium carbonate) rather than gypsum (calcium sulphate) it will have the same effect as lime wherever it is used - this presumably is not a problem where it won't regularly get wet or is not used next to the soil you are growing in (some of the dissolved lime would leach sideways as well as downwards unless a barrier was also installed.)

That's just the chemical "stuff" - I've not used it for paths but I would imagine that it could stick to your boots more readily than other more common alternatives.

[8doubles]

If the chalk gets wet and freezes it is not a good path surface and in summer it can get very dusty.
Many years on Hampshire building sites have taught me a lot about chalk!