PREDETERMINING THE POLISH RESISTANCE OF LIMESTONE AGGREGATES - DISCUSSION

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• Supplemental Notes:
  • No 341, 7 PP, 1 FIG, 4 TAB, 3 REF
• Authors:
  • Nichols, F P
  • Balmer, G
• Publication Date: 1970

Media Info

• Serial:
  • Highway Research Record
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Aggregate gradation; Aggregate mixtures; Blending; Carbonate rocks; Limestone aggregates; Polished aggregates; Sieves; Slipperiness; Tables (Data)
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00211692
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Mar 7 1972 12:00AM