Terrazzo is a form of stone flooring made by embedding marble chips in mortar or grout and then grinding the surface to give a flat and polished surface. The term comes from the Italian word 'terrassa', meaning terrace.
The technique has been used at intervals since the 15th century. It was originally used to exploit scrap marble from other work. The chips were set in clay and sealed with goat's milk.
In the 18th century, Portland cement was used instead of clay.
Terrazzo continued to be a flooring for public buildings and more wealthy home-owners during the 19th century and the Edwardian era, until electric industrial grinders became available in the 1920s.
One method of construction used was to divide the space into a grid with square wooden frames 3-4cm thick. A mixture of marble chips and cement was poured into alternate squares, rolled and trowelled smooth and allowed to harden. The frames were removed and the remaining squares treated in the same way. Grinders and polishers were used to smooth the surface and then the floor was finished with a mixture of wax, raw linseed oil, and turpentine. When dry, the floor was scrubbed with a weak solution of lye (sodium hydroxide) and warm water.
Decorative designs such as borders and floral motifs can be incorporated.