Low temperature process to create brick

The making of durable alkali-activated aluminosilicate brick can be accomplished on a small or industrial scale according to the needs of the community. Brick made with this technology can be obtained in a few hours using a pressurized vessel and elevated curing temperatures (⩾100 °C) or after three to four weeks if the brick is cured under a tarp or in a solar heated enclosure in areas where energy is unavailable. The process is less expensive than conventional kiln firing of brick, because the development of strength vis à vis sintering is a result of a chemical reaction that takes place at a relatively low temperature. Starting materials available in Senegal consist of highly leached aluminosilicate soils (laterites) and tuffs that primarily contain kaolin, and/or or certain by-product materials now considered to be industrial waste (e.g. aluminum refining sludge). The dry ingredients are mixed with just enough concentrated caustic solution to form a thick paste, compacted in a mold, and allowed to cure. Caustic can consist of sodium hydroxide mixed with sodium silicate and water/seawater. The bricks produced in this fashion are durable and relatively inexpensive to make, thus the technology should appeal to those living in villages in less industrialized nations such as Senegal, because the technology uses locally available materials and solar heating that are available almost everywhere.