Construction of terrazzo flooring

Terrazzo is a floor finish of cement and marble chips (aggregate) laid over a concrete base, ground and polished to a smooth, hard, attractive surface.

Materials

• Cement (white or grey, with colour pigments), marble chips 6-12 mm, sand/marble powder.
• Brass or glass dividing strips (3 mm thick, 40 mm deep).
• Oxalic acid and wax for polishing.

Construction method

1. Base: a concrete sub-floor (1:2:4, about 100 mm) is laid and levelled. Its surface is kept rough and cleaned, then wetted.
2. Under layer: a 25-30 mm cement-sand mortar (1:4) bed is spread and levelled while the base is still green.
3. Dividing strips: brass/glass/aluminium strips are fixed in the bed, in panels about 1 m x 1 m, with their tops at the finish level. They stop cracking and form patterns.
4. Topping: a mix of cement and marble chips (1:2 or 1:1.5 by volume; chips 6-12 mm), 6-12 mm thick, is spread in the panels, levelled and well rolled or pressed so the chips show on the surface.
5. Curing: cured under wet sand or gunny for 7-10 days.
6. Grinding: the surface is ground by a machine with carborundum stones: first coarse (No. 60), then medium (No. 120) and fine (No. 320), with water.
7. Grouting: pin holes are filled with a neat cement paste of the same colour and ground again.
8. Polishing: finally polished with oxalic acid powder and wax or polish.

   Section
   ___ marble chip topping (6-12 mm)
   ~~~ cement mortar bed 1:4 (25 mm)
   ... PCC sub-floor 1:2:4 (100 mm)
   --- compacted brick soling / earth
   |brass strip| every ~1 m

Terrazzo is hard, durable, easy to clean, and is used in hospitals, schools and offices.