Making Cement Board

One choice for exterior siding on a building is cement board, which is made from a mix mostly of cement, sand, and fibre. The fibre toughens the board to give it tensile strength and resist cracking. Originally, the fibre used would have been asbestos, but this is no longer used because of its health hazards. Modern cement board uses the fibres from wood pulp instead.

It turns out that the process for making this product is closely related to the process for making (non-corrugated) cardboard. The sand and cement are mixed with the pulp just as one would add fillers when making paper, but in substantially greater amounts. The pulp is spread on a screen belt for draining and several such layers are laminated to make up the required board thickness. The boards are embossed with a wood-grain pattern, cut to size, and steam-heated to cure the cement.

The process can be seen on the How It’s Made channel on YouTube.

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