Create a custom pattern in the Latex package "tikz"

I am working with "tikz" presently and found out is is possible to to fill areas with certain patterns, see p. 217 on https://www.bu.edu/math/files/2013/08/tikzpgfmanual.pdf

Now my question is: Is it possible to implement custom patterns? For example, i need to fill an area with the hatching of concrete, as you can see here: http://www.sema-soft.com/de/forum/files/schraff_886.jpg

Anyone of you tried that before?

Thanks for your help