In the past I have used various plaster products as well as Durham's Water Putty with varying degrees of success. The problem I always had is they all would harden before I was able to get the roads completely smooth and I would be forced to sand down the high spots and fill in the voids.
I got the idea of using tile grout watching a how-to video. A half hour after applying the grout, the excess could still be cleaned up with a damp sponge. That seemed to indicate it would still be workable for at least a half hour so it would give me a better chance to smooth it before it hardened.
I purchased two types of grout. One was a tub of premixed vinyl grout and the other was a bag of powdered grout that had to be mixed with water. I opted for the vinyl grout which had the added advantage of being pre-colored. I bought this at Lowe's and the color was slate gray.
After making the forms for my city streets, I began filling the forms with the grout and tried to spread it using a 5 inch wide putty knife. It quickly became apparent that it was too thick to spread smoothly so I thinned it out with a small amount of water. It didn't take much water to get it to the consistency of pancake batter. After doing one street I waited for a half hour to do the smoothing but because of the added water, it was requiring longer for it to dry enough for this step. I had done this late at night and didn't want stay up until it was ready to be smoothed. By morning it had hardened much like plaster or water putty would have done. I had to sand down the high spots and fill in the voids with thinned grout. I ended up with fairly smooth streets with a slightly gritty texture. The color was a medium gray which I think is just about right as the base color for asphalt roads. I'll use various weathering powders for finish as I always have.
For the subsequent streets I thinned the grout ahead of time. This should be done sparingly as a little water goes a long way toward getting the pancake batter consistency I wanted. I quickly filled in the forms for the rest of the streets and had no trouble getting it fairly smooth. I waited several hours until it was just slightly damp but still workable. I soaked a foam brush in water and used it as a float to smooth down the few high spots and fill in the low spots. When it hardened I had the smoothest best looking paved surfaces I have ever produced and I was able to do this on only my second try. I did discover that a bubble had formed during the smoothing process and this left a small hole in the surface but this was easily filled and smooted with a bit of the grout. I could have made it a pothole patch but decided I can always add that kind of detail later.
I am very happy with the results and I was surprised at how quickly I learned to get good results from this material. I will use this for all future street and road paving and might even go back and redo some roads I am less than happy with. I've never read about using grout to as a paving material although I would bet it has been done. I would certainly recommend giving it a try.
What did you use for forms?
We would like to see pictures.
Henry
COB Potomac & Northern
Shenandoah Valley
I used 1/16" strips of styrene that are slightly narrower than the sidewalks I am going to glue on top of them. For this I will use Smalltown USA sidewalks which are 1 1/2" wide. making the styrene strips slightly narrower allows me to extend the curb of the sidewalk over the paved road. On the corners I cut out a diagonal 45 degree piece where the rounded corner of the sidewalk will be. It's best to clean the excess off the styrene forms before they completely harden but I forgot to do this after the first application but was able to scrap them clean with a 1 1/2" putty knife fairly easily even after the grout had hardened. It didn't damage the paved street when I did this. When the grout dries, it settles slightly below the top of the forms.
For my rural country roads, I will use Woodland Scenics foam N scale roadbed strips for forms turned upside down to create a beveled shoulder. They will easily bend to the curves of the road.
I need to get new batteries for my digital camera and am looking for aFREE photo sharing site. It's been at least a couple years since I last posted any pictures. I haven't done that since Photobucket charged a fee if you wanted to share your photos. I hope to be able to post the photos after I have weathered the streets and added crosswalks and a center line.
I've discovered my Amazon Prime account includes photo sharing. This is just a test to see if I can post the link to a photo.
https://www.amazon.com/photos/groups/g3GTs0LrRlWLWU8yxmnZAQ/collections/9b5c38307e8d6f768b2e2f5531760f65af26e013a69193edca82468e3cd51590
Update: This didn't quite work out like I had hoped. With Photobucket I could just click on the photo and it would create a link with an IMG prefix as I recall. I'm trying to figure out if I can do this with the Amazon app. The photo would appear rather than the clickable link.