Over the last two decades, provision of tiles on the walls and floors of buildings has seen a tremendous upswing. Bathrooms, kitchens, shelves, facades, garden fountains and home accessories find a greater use of tiles these days. However, the only factor that is examined while selecting tiles is their physical appearance. No attention is paid to the technical aspects of the tiles selected which if considered may lead to a better service by them and their negligible maintenance in future. Surface flatness, edge curvature, warpage, surface quality, water absorption, scratch hardness, abrasion resistance, thermal shock resistance, crazing resistance and resistance to action of chemicals are a few such properties which should be examined before selecting for use in residential, public or industrial buildings.
There were times when only 4 inch size white glazed tiles were used to clad the walls of bathrooms up to 7 feet level. Now the tiles have entered even the drawing rooms. Not only glazed but hand made tiles, hand painted tiles, border tiles and even glass embossed tiles in which the pattern that is embossed in tiles is of multi-coloured glass are being manufactured these days. The designs printed over the tiles are computerised and screen-printed. Not only this, one manufacturer has tried to vivify the grandeur of Indus Valley civilisation by producing tiles called Mohanjodaro collection, carrying various symbols discovered during archaeological excavations. Many manufacturers have collaborated with foreign countries to produce quality-tiles. Such a scenario having tough competition and high creativity demands a thorough study of these products before making the final selection.
Size and finish: Now there is a large variation in the size of tiles. Many sizes, varying from 4”x4” to 16”x16” are available. Though the most preferred shapes are rectangular and square, ‘hexagonal and octagonal shapes are also being produced. The finish may be glossy, semi-glossy, matt, luster and of many other types. Table 1 and Table 2 show various sizes and finishes of floor tiles and wall tiles being produced these days.
Colour: There is a revolution on the colour-front. Such a stunning variety of colours is available that it is difficult to count their number. For instance, one manufacturer is producing floor tiles having 99 colours and wall tiles in 282 colours. Not only this, the manufacturers are ready to produce tiles of the colour and shade as per individual’s choice. Even computerised designing as per individual choice is adopted.
Floor tile groups: Tiles used in floors are now categorised into four groups with respect to the service to be rendered and the intensity of traffic on them. These groups are Group-II, III IV and V. While Group-II tiles are for low and light traffic, Group-V tiles are for very heavy traffic. It is better to specify the group with respect to the intensity of the traffic while placing a demand for floor tiles as this will bring durability and economy. There is no fun in using Group-V tiles in an area where traffic is light. It will cause extra expenditure only. Similarly, use of Group-II tiles in areas of dense traffic such as cinema halls, commercial centres, railway stations etc will result in their wearing out soon.
Table 3 shows various groups of floor tiles, their suitability and their areas of application. Group-V tiles combine high hardness with complete acid and alkali resistance together with high abrasion resistance. Under the abrasion resistance test, a set load of Corborandum, water, water and steel balls is applied on the tile surface using a standard abrasion meter. No abrasion has to be visible after 12000 revolutions. Thereafter, the tile is subjected to Mark resistance test. If no mark is noted, Group-V standards are met with. Such tiles are highly suitable for industrial floorings also.
Tile properties: Different properties have been specified for tiles to be used in walls and floors. Bureau of Indian Standards has evolved IS codes — IS 13753 and IS 13755 for wall and floor tiles respectively. European Standard EN-87 enlists the technical features of wall and floor tiles under the Groups EN159Blll and EN159Blla, respectively. Table 4 shows some important properties of these tiles that should be checked before their purchase. While an organisation can get the tiles tested for these properties, an individual can ask the manufacturer or the supplier to show the test certificate for the batch to which the tiles under purchase belong. Tiles being ceramic products, a variation in their length and shade is likely to occur during the firing process. A buyer should therefore be careful towards these properties. Reputed manufacturers should themselves discard tiles having variation in length and shade beyond permissible limits as otherwise their reputation may be at stake. Presence of just a few such tiles may ruin the aesthetic effect of the tiled wall or floor.
In addition to the properties given in Table 4, the resistance of the tile surface to staining by household chemicals and swimming pool salts should be checked as per procedure laid in European Standard EN122. The manufacturer is bound to mention the abrasion resistance class of the tiles on the box containing them. If in doubt, this test can be got carried as per method of testing in EN154.
Thickness, weight and lot: The thickness of floor tiles varies from 7 to 10 mm. Floor tiles are contained in boxes and number 10 to 50 depending upon the size of the tiles. A box having 25 tiles of size 200x200 mm will weigh around 16 kg while another having only 10 tiles of size 400x400 mm will weight 32 kg. Wall tiles have a thickness of 6 to 8 mm. A box containing 25 tiles of size 200x300 mm will weigh 19 kg and one having 40 tiles of size 200x150 mm will weigh 14.5 kg only. The weight of ceramic tiles for a thickness of 6 mm may be taken as 16 kg/m2. Tiles, these days, are pre-polished, repair free and ready to use. This aspect should also be examined while selecting the tiles.
Manufacturing process: The process of manufacturing of tiles has undergone a significant change during the last few years. Earlier, the tiles used to be subjected to multi-firings. First, these were baked at very high temperatures. Thereafter, glazing which consisted of a mixture of Glass and Zirconium or such elements used to be applied on the tiles. Then the tiles were rebaked. The tiles produced these days are single fired i.e. the manufacturing designing and glazing are done in one process thereby producing more durable and maintenance-free tiles. These single-firing manufacturing processes have been brought by the manufacturers to India from the pioneer countries in tiles such as Spain and Italy. Italy still reigns as the king of tiles. In fact the word “tile” itself has been derived from Italian word “Teluga” which means a covering.
Today, as many as 21 reputed companies are producing tiles in India. Table 5 shows their makes and areas of specialisations in alphabetical order. The competition is fierce. The result is that some of the manufacturers are declaring their product as “exclusive” and not decreasing the costs while other are fighting for survival by keeping very little margins. During the last few years, the prices have come down well. Though hand made and hand painted tiles have uneven edges, odd sizes and very bright colours yet are very costly because these involve carving, are not produced on mass scale and considered to be an exclusive and class item.
Terrazzo tiles: Till early nineties, terrazzo tiles remained under most use Composed of marble chips mixed with coloured or white cement, mechanically ground, hydraulically pressed and then finished, cured and polished, these tiles act as somewhat structurally strong members of the building. Terrazzo tiles, however, need to be polished at regular intervals, the weight is heavy and there is always a tendency of their becoming slippery. These days terrazzo tiles have given way to ceramic tiles. A 6 mm thick ceramic tile serves the purpose at a place where a 25 mm thick terrazzo tile has to be used. There is no comparison of the finish as the ceramic tiles provide a highly attractive surface while the terrazzo tiles begin to look ugly after a year or so. There may be a lot of breakage during the transportation and handling of terrazzo tiles. This factor is also taken care of by ceramic tiles.
Laying of tiles: The walls and floors will come alive only if laying of tiles has been done in a proper manner. How-so-ever beautiful or costly the tiles may be, they will lose all the elegance and aesthetic effects if the tile-joints are thick and uneven; cut-pieces are not used at right places and symmetry is not maintained. Cut-tile-pieces should be used only at the ends (never in the middle) of the walls, on window sills and door jambs. Grouting of joints should be done with a water-proof epoxy grout. No excess grout should be left over the tile surface and should be wiped off at the earliest. The base should be checked to be rough before fixing tiles on it. A guide-rod should always be prepared by the mason before start of work. This guide-rod should carry the markings of tile-size and gaps for grouting among them.
Whenever a laid tile gets broken, it should be removed in a very patient manner by using a chisel and hammer and without affecting the adjacent tiles. Breaking should always be started at the centre of the tile and not from edges. After the removal of tile, the base mortar should also be chipped off. Grouting of the joints should be done when the fixed tile has sufficiently dried up.
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