Clinkers are the intermediate nodular product produced in the kiln before grinding; they are classified under 252310 regardless of their intended end use. Once ground and blended with gypsum or other additives to produce a finished cement, the product moves to the appropriate finished-cement subheading such as 252329 for grey Portland cement.

If a product is a prepared construction mixture — for example, a pre-mixed mortar or concrete admixture — it may be classified outside this heading under the chapter covering prepared binders or construction preparations. The key test is whether the product is still a hydraulic cement in its own right or has become a formulated mixture with other functional ingredients.