Blast furnace slag is produced in large quantities at works processing iron ore. The slag is basically the remains of the ore, lime and coke from the furnaces. This is considered to be a usable pozzolana and can be used in mixtures with lime and Portland cement, see pages 94-95. Before it can be used it has to go through a process of quenching and granulating.
It is also possible to produce an expanded 'slag wool' which can be used as thermal insulation in the same way as mineral wool. The constituents of blast furnace slag increase the level of radioactive radon in a building, though the levels are generally quite negligible.
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