What is "road crush"? 1

[nastom]

Can anyone help me? I'm building a solar heated green house and have been told to cover my hot air ducts with "road crush" which is supposed to be a mixture of agregates and clay which while providing good drainage will also retain a high moisture content. None of the road people in my area have ever heard of it. Is this a western US term? Crusher run (which people do use arround here) has too many fines and will not allow good drainage.

Is there another name for "road crush" or can someone describe it better?

 

[SirAl]

In my neck of the woods, when one speaks of 'road crush', I instinctively envision a relatively coarse graded road surfacing gravel (3/4" max. nominal size to 1-1/2" max. nominal size) that would be encountered on a typical open gravel surfaced road. I am totally unfamiliar with the application that you reference although terminology may vary from location to location. I would ask for specifications then talk to local aggregate suppliers to determine if they have a product that would meet those specs.

 

[Grouser]

nastom
Why do you need both a high moisture content and good drainage? Is the moisture content requirement to trap heat transferred from the ducts to the soil or is it for high humidity in the green house, or both? Why not use something that will retain moisture and design a system to remove excess water rather than trying to have one material to do both? A free draining sponge is a contradiction in terms. You may be able to place a moisture retaining soil surrounding the ducts and more porous soils elsewhere to relieve excess moisture. On the other hand, a pair of boots outside the green house door may be cheaper.

Good Luck!