Question
Hello William
Ok, I know this is a tough one. I have a concrete patio about 5m x 5m that I want to cover with a light grain gravel. The reason being that the concrete looks horrible. What I want to know is, I think there is a method for laying a substrate of bitumen or resin adhesive, and then coating it with the gravel to a thin layer.What do they use and where could i get this substance from and is it a special gravel they use

Answer
I am assuming you want to do it yourself, instead of hiring someone else to mess with it.
I have also seen a number of 揻ranchise opportunities?for this product in the back pages of Entrepreneur & other business magazines.  

Concrete polymer overlay or thermosetting resin concrete is a mix of resin, sand, and gravel (the gravel being the colored aggregate that you want to achieve):

Here are a few websites that may be helpful.

http://www.distinctiveconcrete.com/products_overlays.htm

Or other concrete resurfacing websites:

http://www.qcfamily.com/concrete/index.htm

http://www.concretebeauty.com/

http://www.resealconcrete.com/

http://www.concretesolutions.com/

And here is their  SPECIFICATIONS for the surface-bonding mix of a thermosetting resin mix:
http://www.concretesolutions.com/pdfs/POLYMER%20PATCHING%20MIX%20Spec%20Sheet%20...

Quikcrete even offers a concrete-resurfacing product, and it is available at Ace Hardware.  I don抰 know if you can spread aggregate over it, before it sets up.  Here in my harsh weather area, the aggregate rock tends to pop out, if it is too small a size.

Good luck!  -Marc