2517 Pebbles, gravels, and broken stones, round stones, and flint commonly used for concrete aggregates, paving, railway roadbeds, or other roadbeds, whether or not heat-treated; Slag, floating slag, and similar industrial residues, whether or not mixed with the materials listed in Part 1 of this code; Asphalt crushed stone, fragments, and powders of various stones listed in heading 25.15 and 25.16, whether or not heat-treated: HS code chinese tariffs