Terrazzo flooring is a special type of concrete flooring in which marble chips are used as aggregates, and this concrete on polishing with carborundum stone presents a smooth surface. Any desired colour can be obtained by using marble chips of different shades and sizes and also by using different coloured cement. The aggregate shades are exposed by grinding the surface. Normally, terrazzo mix having proportions 1:2 to 3 (1 cement : 2 to 3 marble chips) depending upon the size of marble chips, is used.

The terrazzo flooring is becoming very popular these days for providing floor finishes in banks, hostels, office buildings and other public or social buildings, on account of its excellent wear-resisting properties and decorative effects.

Terrazzo finish is atleast 10 mm thick and comprises a mixture of desired cement (i.e, coloured cement), marble powder and coarse aggregate, such as chippings of marble, quartzite, pearl, glass, etc., of selected colours and of sizes graded from 2 mm to 8 mm. Sometimes, larger particles up to 10 mm are used. This terrazzo finish is installed over the concrete base course in following two ways or methods,

In one method, the cement concrete base is covered uniformly by a 6 mm sand cushion, over which a tar paper is placed. On this paper, a layer of rich mortar (1:3) about 30 mm thick is deposited.

In another method, terrazzo finish is applied monolithically. First of all, a thin coat of cement is spread over the wet concrete base. This layer is then swept with a broom and a layer of cement mortar (1 cement : 2 sand) 12 mm thick is evenly spread immediately over it.

The metal dividing stirrups, about 30 mm in width and 1.3 mm in thickness, are inserted on edge in the mortar bed in desired patterns before it hardens.

When the mortar bed has sufficiently hardened, a terrazzo mixture (1 cement : 3 marble chips), 6 to 12 mm thick, depending upon the size of chips, with water just sufficient to make a workable mix for the mosaic finish, is applied. This terrazzo layer is then rolled lengthwise as well as cross wise. About 85% of the marble or aggregate should be exposed over the finished surface and to achieve this, it may be necessary to add additional chips during the rolling process.

After curing for several days, the surface is carefully polished by means of a grinding machine fitted with carborundum grinding stone disc. During the process of grinding, the surface is kept wet. Holes or pores, if any, are filled with a thin grout of cement paste, having same tint as the terrazzo finish. After this, the surface is again cured for few days and finally ground by grinding machine fitted with a finer carborundum stone disc. Finally, the whole surface is washed with a weak solution of soft soap in warm water. The surface, so produced, is pleasing in apperance and sanitary in nature.



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