Base Material 1
I began with a foundation material. I grabbed a pack of tileable sbp textures over from Textures.com and applied them to a VrayMtl. I used 2 color correction maps to create a light and dark version of the diffuse texture and blended them using a composite map.
I find the VrayDistanceTex to be a great tool to mask the dark texture, by telling vray to apply the dark version 24" from where the asphalt meets the ground/curb, and thus create the sense of dirt building up at those edges. I also used a grunge map on the distancetexture slot to add a little bit of variation. VrayDistanceTex map is one of those handy tools that can make our otherwise boring materials have more complexity and realism.
Other than that I have a Normal Map and a Bump map attached to a VrayNormalMap Texture. Don't forget to set the main mtl bump settings to 100 and remove the filtering from the bump texture itself for added fine grainy detail.
The reflect color swatch is set to pure white and I use an output to modify the asphalt texture and use that to control the reflection glossiness by playing with it's brightness/contrast.
The displacement map is attached but not activated. I solely attach it to the main material to keep my material organized. I will later attach the displacement map to a seperate VrayDiplacementModifier that I will add directly to the road surface itself.