... %Table-2 Physical properties: Nominal size1/25/83/411.52312mm16mm19mm25mm38mm50mm76mmNumber per m3610,000269,000146,00059,00019,6808,2432,400Package density(kg/ m3 ... )780700670630580550530Free volume(%)68717577807975Surface area(m2 /m3 )64753535025418012091Specific gravity(g/ m3)2.3Water absorption(%)0.3Acid resistance(%)>99 ...