You say that you have use road a road bonding agent.
Is what you have used like a prime or tack coat? ( A bituminous mixture similar to tar, but spray applicated )
That usually works well in most areas, we build complete roads out of essentially gravel and tar ( slag roads ). Chip seals are essentially gravel and tar as well.
Start with a solid subgrade, prime it, gravel it, tar it, gravel it. That is an oversimplification, but it is the basic premis. Different size gravels are laid ... usually consisting of 57 stone
And it is not specifically tar.. there are other liquid asphalt or oil emulsion mixtures.
Soundguy