How to Lay In Situ Terrazzo (Marble Chips) Flooring? [PDF]

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The terrazzo flooring is a composite material consisting of chips of marble, quartz, granite, glass, or other suitable material, mixed with a cementitious or polymeric binder, and poured to form flooring. The flooring is grounded and polished smooth to produce a uniformly textured surface.

The procedure/methodology to lay the terrazzo flooring is discussed in the article below-

Materials of Terrazzo Flooring

1. Aggregate

The aggregates used in terrazzo flooring consists of chips of marble, quartz, granite, glass, or other suitable material with size varying from 1 mm to 25 mm. The marble powder used in the topping of terrazzo flooring shall pass through the 300-micron sieve.

1. The aggregates used in the topping layer of the terrazzo flooring shall be hard, sound, dense and homogeneous in texture with crystalline and coarse grains.
2. It shall be uniform in color and free from stains, cracks, decay, and weathering.

2. Color Pigments

The color pigments used in the terrazzo flooring shall be of permanent color. The proportion of color pigment with cement conforms to the requirements mentioned in Table 1.

Table 1: Cement pigment proportion for various colors of matrix in Terrazzo flooring

Colour of cement	Pigment to be used	Proportion of pigment	Proportion of cement	Proportion of white
Red	Red oxide of iron	1	15-20	Nil
Black	Carbon black	1	25-40	Nil
BottleGreen	Green Chromium oxide	1	15-30	Nil
Pink	Red oxide	1	Nil	100-300
Cream	Yellow oxide of iron	1	Nil	100-400
Yellow	Yellow oxide of iron	1	Nil	25-75
Light Green	Green chromium	1	Nil	50-150
French Grey	--	Nil	1 to 2	1
Fawn	Yellow oxide of iron	1	6	4

3. Dividing Strips

The material used for flooring shall be similar to that of flooring having the resistance to wear. The material of dividing strips shall be of aluminum, brass, copper, and glass, plastic, or similar materials. The strips shall be protected with a bitumen coating. The size of the strip shall be not less than 1.5mm in thickness and not less than 25mm in width.

General Specification of Terrazzo Flooring

The general specifications of terrazzo flooring are listed below-

1. The terrazzo flooring consists of 2 layers, the base layer of concrete or the cushioning layer and the top layer of terrazzo aggregates.
2. When the terrazzo flooring is laid over the ground shall consist of the layers as shown in figure 2.
3. While the flooring laid on the structural slab shall have an arrangement as shown in figure 3.

4. Sand is preferred for the sub-base which shall be well compacted and lime concrete shall be preferred as cushioning layer.
5. Dry lean concrete of 1:5:10 shall be laid as the base course of a thickness not less than 100mm.
6. The thickness of the underlayer and topping for flooring combined shall not be less than 30mm.
7. The thickness of the terrazzo topping layer shall be not less than the following depending upon the size of the chips used as given in table 2.

Table 2: Size of chips and thickness of topping layer.

Size of chips (mm)	Minimum thickness (mm)
1 to 2 2 to 4	6
4 to 7	9
7 to 10	12
> 10	not less than 1 1/3 times the maximum size of chips.

Mix Proportion of Underlayer and Topping Layer

1. The mix proportion of underlayer shall be of cement concrete mix 1:2:4 by volume and the size of aggregate shall not exceed 10mm.
2. The mix proportion of the terrazzo topping layer shall be three parts of cement and one part of powder by mass.
3. For every part of the cement marble powder mix, the proportion of aggregates shall be as in table 3 depending on the size of aggregates.

Table 3: Proportion of aggregate depending on the size of aggregate.

Size of aggregates parts (mm)	Proportion of aggregate of binder mix
1 to 7	1 ¾
7 to 1515 to 22	1 ½

4. The proportions of cement shall be inclusive of any pigments added to the cement.

Procedure of Laying In-situ Terrazzo Flooring

1. Mixing of Materials

1. To achieve a uniform appearance, it is essential to mix the materials thoroughly.
2. It is recommended to mix the chips well in the required proportions of various colors and sizes when different colored chips are used.
3. When white cement is used, the pigment and cement shall be sieved and mixed in the required proportions thoroughly with marble powder and aggregates.
4. At the time of mixing, the aggregates must not be heaped, which would result in the coarsest chips moving to the edge of the pile and cement working to the center at the bottom.
5. The mix shall be thoroughly mixed in the dry state, later to which the water shall be added in small quantities to achieve proper consistency.
6. Machine mixing is preferred for mixing, but the common type of concrete mixer is not as suitable for terrazzo work as the mixer specially made for this purpose, in which segregation is prevented by blades.
7. The pot life of the mix is not more than half an hour of the addition of water during preparation within which it must be laid.

Under-Layer of Terrazzo Flooring

1. The cement concrete of the design mix shall be used, as discussed in the above design mix heading.
2. The panels shall be of uniform size, not exceeding two sqm in area or two m in length for inside situations.
3. In exposed situations, the length of any side of the panel shall not be more than 1.25 meters.
4. Cement slurry at 2.00 kg per sqm shall be applied before laying of underlayer over the cement concrete / RCC base.

Fixing of Strips

1. A 4 mm thick glass strips or 5 mm thick plain asbestos sheet or 2 mm thick PVC strips/aluminum strips /brass strips shall be fixed with their top at the proper level to required slope.
2. The strips of stone or marble or any other material of specified thickness can also be used if specifically required.

Laying of Topping Layer of Terrazzo Flooring

1. All the topping materials, coloring material, cement, marble powder, and marble chips are dry mixed thoroughly.
2. The dry mortar is then mixed with water by adding the water in fine sprays till the mortar is homogeneous, stiff, and workable.
3. The terrazzo topping must be laid when the underlayer is sufficiently hard enough to prevent the cement from traveling to the surface, and the underlayer is still plastic.
4. The topping layer shall be slightly more in thickness than that specified to achieve uniform thickness after compacting.
5. The surface shall be brought to the required thickness by trowelling and pressing with the help of a straight edge and steel floats.
6. It must be carried out in such a manner that the maximum amount of marble chips are visible and evenly spread over the surface.

Polishing, Curing and Finishing of Terrazzo Topping Layer

1. The polishing of toping layer shall be strictly carried out by machine means after 36 hours of laying the top layer.
2. The surface shall be watered and ground evenly with machine fitted with special rapid cutting grit blocks of coarse grade till the marble chips are evenly exposed, and the floor is smooth.
3. After the first grinding is completed, the surface shall be thoroughly washed to remove all grinding mud and covered with a grout of cement and coloring matter in the same mix and proportion as the topping in order to fill any pinholes that appear.
4. The surface shall be allowed to cure for 5 to 7 days and then rubbed with machine fitted with fine-grit blocks and cured again for three to five days.
5. Finally, the third grinding shall be carried out with a machine fitted with fine grade grit blocks to get even and smooth surface without pinholes.

FAQs on Terrazzo Flooring

Read More:
1. 5 Special Types of Flooring used in Building Construction
2. Types of Flooring Materials and Their Applications in Building Construction