Physical properties Brand SK-32 SK-34 SK-35 SK-36 SK-38 Index Refractoriness íµ 1730 1750 1770 1770 1790 bulk density g/cm3 2.15 2.2 2.3 2.35 2.52 Apparent porosity ¿Q% 24 24 23 23 23 Cold crushing strength ¿RMpa 30 35 40 45 65 Refractoriness under load (0.2MP) íµ 1350 1350 1400 1450 1550 Permanet liner change 1500íµ 2hrs% +0.2to-0.2 +0.2to-0.2 +0.1to-0.4 +0.1to-0.4 +0.1to-0.4 Thermal expansion at 1000 íµ 0.5 0.5 0.5 0.5 0.5 Fe3O4% 1.96 1.93 1.9 1.87 2 Al2O3% ¿R 42 48 55 60 65 SiO2 48-50 46-48 41-44 37-40 27-30