Generally, for cheap and on-site production of waterproofing, a combination of aggregate chippings and aggregate dust is combined with bitumen emulsion and is completely laid over the constructed road. The emulsion itself can vary in type.
Other than this, there are waterproofing solutions manufactured for roads (bituminous roads). Some common ingredients that I know are :
- Oil bitumen, petroleum bitumen, emulsified bitumen, organic solvents
- Aggregate chippings, rubber crumbs, mineral fibres and plasticizers.
There may be more, but these are a few common ones.