Type		high alumina
Items		B1	B2	B3	B4	B5	B6	B7
physical properties	Permanent linear change  ≤	900	1000	1100	1200	1300	1400	1500
	Bulk density	0.7	0.7	0.75	0.8	0.8	0.9	1
	Cold crushing strength   ≥	2.4	2.4	2.4	2.4	2.4	3	3
	Thermal conductivity    ≤	0.2	0.21	0.23	0.26	0.27	0.31	0.36