Fibre cement composites are composed of Portland cement, silica, water and wood pulp which was manufactured by “ Hatschek process”. The Hatschek process was initially developed for the production of asbestos composites, but it is now used for the manufacture of non-asbestos, cellulose fibre reinforced cement composites.
In the Hatscheck process, unbleached cellulose fibers are re-pulped in warm water; the re-pulped fibers are refined and then mixed with cement, silica, and other additives to form a mixture. The fibre cement mixture is deposited on wire cylinders then the solid matter is transferred onto a felt belt. After that, the solid sheet is transferred onto a laminating roll and this process is repeated. Multiple layers of sheets are laminated until the desired thickness is reached. The laminated green sheet is cured to form a fibre cement product.
Fibre cement products offer numerous advantages over other traditional materials such as wood siding: they are weatherproof, fire and termite resistant, flexible, highly workable and durable, especially autoclaved fibre cement products. In an autoclave, calcium silicate based composites are manufactured by applying intense heat and pressure to enhance chemical reaction between cement and silica to form fibre cement composite materials. This leads to fibre cement composites with superior properties than air-cured fiber cement composites, for example strength and toughness, low moisture movement, low alkalinity, high fire resistance and good workability. In addition, pigment can be added to make fiber cement products of various colors.