Papercrete is a building material that consists of re-pulped paper fiber combined with Portland cement or clay, as well as other soils. First patented in 1928 by Eric Patterson and Mike McCain (who originally named it "padobe" and "fibrous cement"), it was revived during the 1980s. It is generally perceived as an environmentally friendly material due to the significant recycled content, although this is offset by the presence of cement, which emits CO2 during manufacture. The material also lacks standardisation, and proper use therefore requires care and experience. However the inventors have both contributed considerably to research into developing the necessary machinery to make it, as well as methods of using it for construction.
Manufacture The paper used in papercrete can come from a variety of sources, including newspaper, junk mail, magazines, books. A mixer is used to pulp the mix before this is combined with cement or clay. Depending on the type of mixer, the paper may need to be soaked in water beforehand.
Properties The name papercrete arises from the fact that most formulas use a mixture of water and cement with cellulose fiber. The mixture has the appearance and texture of oatmeal and is poured into forms and dried in the sun, much like the process for making adobe. Dried papercrete has very low strength, but fails by slow compression (due to the large air content and hence compressibility) rather than in a brittle manner. Concrete and wood (though dry soft wood can be as high as R-2 per inch, high moisture content reduces this value markedly) are not known for their insulating qualities; however, papercrete also provides good insulation. Papercrete's R-value is reported to be within 2.0 and 3.0 per inch (2.54 cm); papercrete walls are typically 250 to 300 mm (10–12 in) thick. Unlike concrete or adobe, papercrete blocks are lightweight, less than a third of the weight of a comparably-sized adobe brick. Papercrete is generally mold resistant and has utility as a sound-proofing material, however mold can develop if the material remains warm and moist for too long. Dried, ready-to-use papercrete has a rough surface. This increases its surface area and provides a very strong bond from one block to the next. Additionally papercrete's ready moldability provides considerable flexibility in the designed shape of structures, for example domed ceilings/roofs can be easily constructed using this material. When properly mixed and dried, the papercrete wall can be left exposed to the elements. In its natural state, it is a grey, fibrous-looking wall. For a more conventional look, stucco can be applied directly to it. Papercrete construction has the advantage of being relatively low-cost, as materials are cheap and widely available. Furthermore, machinery suitable for small-scale construction is simple to design and construct.
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