I am trying to make a dirt road that looks like it has been dried from the muck of the rainy season but is still being tore up by heavy horse traffic.
Old time dirt roads in the transition era between horses and cars look like this in the rainy season. The horse traffic tears up the surface. The horse hooves break up the surface and leave clods as it starts to dry.
Here is a latter picture showing a clay surface, notice the clay clods. The tracks formed are distinct.
Here is a dirt not clay road note the distinct tire track.
Here is my original attempt.
Tile grout from a home improvement store.
I discovered that tile grout mixed with latex paint would form claylike clods.
I mix tile grout with my base clay colored latex paint until it was the consistency of wet sand. Keep stirring the mix until it is dry but don't break up all the clods. It takes about a week for this much to dry.
Spread the "clay" mixture out on the road area. Break up the bigger "clods" by rubbing them between the fingers.
Make wheel grooves with a model wagon or car.
I sprayed the mixture with cheap hair spray in the pump bottle. Let that dry. This helps hold the shape of the ruts while it is misted with water.
Then I misted the road with "wet" water until it was wet. "Wet" water is water with a small amount of wetting agent. I use liquid detergent.
Dribble a solution of white glue and water on the road. I use a 2:3 glue to water solution.
If you are doing a road traversed by horses add a small deposit of horse manure. I use dyed sawdust applied while the glue is still wet.