Any recommendations on this? I thought of sandpaper but it is too uniform.

Could you be more specific? Asphalt? Cobblestone? Muddy? Muddy with ruts? Dry dirt road, with a lot of traffic between rains?

standard dry asphalt, very dark grey. Maybe I could make it with texture paste, but how do I get the pebbly look?

Verlinden produce a nice asphalt sheet in resin but apart from that you are probably best to make a roughly level area using plaster and then add some texture to it. Tamiya Texture paint is very useful for this and dries rock hard.

I use a thin layer of wall spackle (plaster, wall repair, etc.). Spread it on and smooth it out. In 1/35 scale, you can't se the individual pebbly texture. When dry, sand smooth and paint it with a dark grey. Then weather and it will look great.

Some examples.

Arizona Rock and Mineral's Asphalt paving material is rather good. I use this stuff for model railroading. Just scale your road width to the correct size, cut a strip of styrene sheet to the dimensions and lay the rock product over it. Bonded with 1/3 water, 1/3 alcohol, 1/3 matte medium.

here's all the info you need for correct road dimensions.
http://mutcd.fhwa.dot.gov/

Fifer Hobby sells the product.
http://www.fiferhobby.com/html/arizona_rock_and_mineral.html

This was a test strip I worked on when I first got the product.



Compare to actual asphalt
al asphalt.

Sand paper of the proper grit and sprayed to match a section of asphalt is about as good as it gits. You have to spray the marking lines and the darker and lighter areas caused by tire wear and oil spatter.

2mm black foam sheet, can be purchased at Amazon or craft stores. Paint / weather as you like. I use masking tape after painting lighter grays on top to tear off the paint and leaving a very nice worn / mottled look. You might get a similar effect with a sponge but I prefer this way. After painting, striping, etc. use a dremel or similar tool to cut cracks, chips, and holes. Practice first on a spare. This allows precise control a little better than using spackle. You may need to zoom in to see the detail.

If you want to go cheap, I recommend Rotten Stone, which should be available at any good hardware store. I learned about this technique during my model railroading days, from an author named Lane Stewart. It works for heavy rust as well, and is simple to do. Rotten Stone is a micro-pulverized granite, with a natural gray color used in polishing stone, metal and ceramic surfaces. Basically, you dullcoat whatever object you want to look rusty (or "asphalty" in this case) and while still wet, drop it into a bin of rotten stone which is then sealed tightly and shake. I use Midwest plastic sheet for roads or concrete panels. I've also used sheets of artist mat board, by spraying the board with a fixative like dullcoat, spreading a thin layer of rotten stone on it, and shaking off the excess after a few minutes into a larger bin. A dust mask is recommended when doing this, as it can get a little dusty if you spill some. You can build up the rotten stone with subsequent layers until you achieve the desired effect. It can then be painted either with airbrush, spray can, or a simple wash. I do recommend painting the work the desired shade before treating it with rotten stone. This works equally well for rusted out surfaces. Lane Stewart's work can be seen at Caboose Hobbies in Denver, if anyone is interested. Rotten Stone is cheap, and a 1lb box has lasted about ten years for me. VR, Russ