Early cylinders were completely filled with a porous filler material consisting of diatomaceous earth, charcoal, asbestos, and cement.

每个钢瓶都彻底填满了由硅藻土、木炭、石棉和水泥组成的多孔渗水材料。

youdao

Nothing was done to preserve the past and many of the huts, which had been thrown up in a hurry, filled with asbestos and never built to last, were allowed to rot away.

BBC: Bletchley Park enigma code huts prepare for restoration