Agree with BigH that solid density is maximum theoretical density which, for a 1 cubic foot volume would be the specific gravity times the unit weight of water. Assuming a specific gravity of 2.65, that would yield a maximum theoretical density of 165.36 pcf. For a specification of 80 percent of that, you would need an in-place density of 132.29 pcf.....a practical impossibility for most soils! I have not seen that term used in conjunction with a compaction requirement, but then I'm in the US so we use a different requirement as you noted.
Bulk density is a more elusively defined term. One definition, as given by BigH, is the wet unit weight. In that context you could determine the wet bulk density and then as BigH noted, a dry bulk density.
The maximum dry density is determined by a laboratory test known as a moisture-density relationship. It is the peak of a curve developed by compacting in the lab with a repeatable, known energy input done at various moisture contents to develop both the maximum dry density and the optimum moisture content....the moisture content at which the peak of the curve is defined graphically. This test is commonly called a "Proctor Test" or Laboratory Proctor, named for the developer of the test, R.R. Proctor.
I have attached a brief description of using a Proctor Test. A similar description is contained in the textbook "Principles and Practices of Commercial Construction", 9th Edition; Woods, W. Ronald; Andres, Cameron K.; and Smith, Ronald, Prentice-Hall, 2014.....however, that version is copyrighted and cannot be posted here.
