Technique for using grout

[unittrain]

Just about got my truss bridge done and now want to start some scenery on the embankment I'm using foam for my embankment, I'm going to use a grout mixture for the dirt should I first brush on my white glue mixture then sprinkle the grout? Or apply the grout and mist the glue onto the grout? After the grout down I'm adding ground up leaves to the embankment.

[RBrodzinsky]

Depends on the texture you want.  I always first brush on the white glue, but then, sometimes add glue after if I want a "smoother" surface.  The trick with grout and adding the glue afterwards is to make sure you don't get craters forming.   Suggest practicing on some scrap, first, with both techniques. 

[Ed Kapuscinski]

I've developed a couple of techniques for using UNSANDED grout for dirt.

I guess I go overkill with it, but here's what I do.
First I paint on a layer of paint and glue (craft paint and white glue). I usually jus squirt it on in big loops, and mix it around together with my brush. I usually mist this with some water to thin it out a bit to make it spread easier.
Then I sift the grout down on top of this wet mess.

Finally, depending on the circumstances, I do one of the following:
Brush the unglued stuff into some sort of containment vessel to collect and re-use.
Vacuum the unglued stuff up (use a vacuum with a really good filter, otherwise, dust everywhere).
Use a piece of broken off foam to pat the unglued stuff down flat, mist it with a water/alcohol mix, and then drip some glue into it. If it looks bumpy, you can sprinkle some more down too.

All of this takes some practice to get right, so I'd recommend using some scrap foam or something and practicing before you commit to the layout.