Curly Red Haired Girl At The Brick Wall

With extruded bricks the clay is mixed with 10-15% water (stiff extrusion) or 20-25% water (soft extrusion). This is forced through a die to create a long cable of material of the proper width and depth. This is then cut into bricks of the desired length by a wall of wires. Most structural bricks are made by this method, as hard dense bricks result, and holes or other perforations can be produced by the die. The introduction of holes reduces the needed volume of clay through the whole process, with the consequent reduction in cost. The bricks are lighter and easier to handle, and have thermal properties different from solid bricks. The cut bricks are hardened by drying for between 20 and 40 hours at 50-150 °C before being fired. The heat for drying is often waste heat from the kiln. European style extruded bricks / blocks are use in single wall construction with an applied finish inside and outside. They have many voids, the voids being a greater fraction than the solid, with thin walls of fired clay and come in 15-25-30-42-50 cm widths. Some models have very high thermal performance suitable for Passivhaus type buildings.
Calcium silicate bricks
The raw materials for calcium silicate bricks include lime mixed with quartz, crushed flint or crushed siliceous rock together with mineral colourants. The materials are mixed and left until the lime is completely hydrated, the mixture is then pressed into moulds and cured in an autoclave for two or three hours to speed the chemical hardening. The finished bricks are very accurate and uniform, although the sharp arrises need careful handling to avoid damage to brick (and brick-layer). The bricks can be made in a variety of colours, white is common but pastel shades can be achieved.
It is very common in Sweden, especially in houses built or renovated in the '70s. It is referred to as "Mexitegel" (en: Mexican Bricks).