Papercrete is a material originally developed 70 years ago, and recently rediscovered. It is classified in the category of fibrous cements and it consists of paper, water, cement, and sand. Its use is limited to experimental and recreation purposes, it lacks approval by the International Building Code (IBC). A standard mix has not been established, making the efforts towards standardization even more difficult.
Each ingredient has a different role in the mix. Paper comes from a variety of sources and is usually without cost. Newspaper is most commonly used because it produces consistent results. When paper is mixed with cement, it creates a hard shell and the final product is both lightweight and strong. Fibres also improve the sound insulation properties. Portland cement is the integral component of the mix. Cement reduces the drying time and the effect of shrinkage and increases the strength. However it adds weight to the mix and reduces the flexibility. Cement is also a drawback to materials characterization as green because it releases a lot of CO2 into the atmosphere. Adding aggregates (sand, dirt or pumice) increases the volume and the mineral content. Sand adds thermal mass, makes the mix stronger and more impervious to water but results in heavier structure and reduces R-value.