Nsapato zapamwamba-zopangidwa ndi njerwa za aluminiyamu ndi mtundu wa zinthu zooneka ngati zomangira zomwe zimapangidwa powotcha dongo loyatsa kapena zinthu zina zomangira kutentha kwambiri; iwo ndi a aluminosilicate mankhwala banja. Njerwa zomangira ndi zinthu zosakhala -zopanda zitsulo zomwe zimapezeka m'mitundu yosiyanasiyana, kuphatikiza{3}}alumina, dongo, magnesia, corundum, mullite, ndi njerwa za silicon carbide. Chifukwa cha mphamvu zake zonyezimira zapamwamba, njerwa zapamwamba-zikugwiritsidwa ntchito kwambiri pakati pa mitundu yosiyanasiyana ya njerwa zomangira. Malinga ndi miyezo ya -yapamwamba kwambiri ya aluminiyano refractory, zomwe zili mu Al₂O₃ ndiye mulingo wofunikira kwambiri. Makamaka, njerwa zapamwamba-zimagawika m'magulu atatu: Gulu I (Al₂O₃ content > 75%), Gulu II (Al₂O₃ zili pakati pa 60% ndi 75%), ndi Giredi III (Al₂O₃ zili pakati pa 48% ndi 60%).
Monga mtundu wa zinthu zomangira, njerwa zapamwamba-zikuluzikulu za aluminiyamu zimapangidwa ndi Al₂O₃. Poyerekeza ndi njerwa zadongo ndi semi-njerwa za silika, -njerwa za aluminiyamu zazitali zimanyezimira kwambiri ndipo zimayikidwa m'gulu la -zinthu zokanirira kwambiri. Zomwe zili mu Al₂O₃ zimawapangitsa kukhala pafupi-zosalowerera ndale, zomwe zimapangitsa kuti asakokoloke chifukwa cha acidic komanso ma slags. Komabe, ndikofunikira kudziwa kuti ngakhale ali ndi SiO₂, kukana kwawo ku slag ndikotsika pang'ono pokana kukana kwawo acidic slag. Kutengera ndi zomwe zili mu Al₂O₃, njerwa zapamwamba-zikhoza kugawidwa m'magiredi monga 55, 65, 75, ndi 80.
Njerwa zapamwamba-zosanjikiza zimayikidwa m'magiredi osiyanasiyana kutengera zomwe zili mu Al₂O₃ (aluminium oxide). Zina mwa izo, njerwa za corundum{{2}zokhala ndi aluminiyamu yokwanira 90% kapena kupitilira apo-zimaimira gawo lapamwamba kwambiri- la njerwa za aluminiyamu. Njerwa za "Special grade" zapamwamba-zimakhala ndi aluminiyamu osachepera 85%, pamene njerwa za Grade I zimakhala ndi 75%; Njerwa za Grade II ndi Grade III zimakhala ndi 65% ndi 55% aluminiyamu, motero. Makalasi osiyanasiyanawa amapereka katundu wosiyanasiyana kuti akwaniritse zofunikira zamakampani osiyanasiyana. Njerwa zazitali-zikuluzikulu za aluminiyamu ndi zamtundu wa aluminiyamu oxide (Al₂O₃) zomwe zimadutsa 48%. Zinthu za Al₂O₃ zikafika 90% kapena kupitilira apo, zimasankhidwa ngati njerwa za corundum{18}}zosiyanasiyana{19}}njerwa za alumina zomwe zimachita bwino kwambiri. Ndizofunikira kudziwa kuti miyezo yapamwamba-ya njerwa za aluminiyamu imatha kusiyana m'maiko onse chifukwa cha kusiyana kwa zinthu zomwe zilipo.
Mwachitsanzo, m'mayiko a ku Ulaya, zinthu zochepa za Al₂O₃ pazapamwamba-zozimiririka ndi alumina zimayikidwa pa 42%. Ku China, komabe, njerwa zapamwamba-zikuluzikulu zimagawidwa m'magulu atatu: Njerwa za Grade I zimakhala ndi 75% Al₂O₃; Njerwa za Grade II zili ndi pakati pa 60% ndi 75% Al₂O₃; ndi njerwa za Grade III zili ndi pakati pa 48% ndi 60% Al₂O₃.