I'm clueless as to what you may have on hand to put with it. When you say "smooth" I'm assuming it may be a bit like moist clay (not very porous, retaining a lot of moisture) — almost a kind of mud? It should be able to aerate pretty well when mixed with some coarser material.
I'll just mention how I successfully mixed materials for some raised beds in out
greenhouse. I had compost, and we've got lots of extremely sandy soil on our place. Up the highway about 5km there was a guy who was trenching a field of natural sedge-peat soil and making pick-up loads available for an affordable price. So I made up our beds from a combination of those three materials.
That's just a "for instance" so I'm not sure how it will help you. There was certainly a lot of organic material in the mix I made, so to it I just added amendments like green sand (for potassium), gypsum (for calcium), and some volcanic rock powder (trace minerals). Though I was making a limited amount for the beds, a mixture of this type could act as a (somewhat non-specific) "fertilizer" worked into the upper layer of garden soil.