Lightweight building prods. made of expandable clay - where moulded blank contains holes closed during baking by expansion of clay

摘要

A mixt. is made of the clay and an opening material (a); and the mixt. is made into a moulding contg. numerous parallel holes extending right through the moulding. Hot gases are then fed through the holes so the latter close at least partially. The holes near the periphery of the moulding are pref. fed with a reduced amt. of hot gas; or no hot gas; or with gas at a lower temp. than that used for the remaining holes. The outer zones of the moulded blank are pref. made of clay with reduced expansion characteristics and/or a reduced amt. of opening material (a). The moulded blanks are pref. laid on kiln cars so gas passing through side channels in a tunnel kiln flows through the holes in the moulded blank. Used in the mfr. of bricks or blocks, etc. with a wt. of 0.5-0.7 kg/litre.