Theoretical back ground
Cement concrete flooring tiles shall be of two classes as given below depending on the duty they perform.
A. General purpose tiles
Used for flooring in such places where normally light loads are taken by the floors such as office, buildings, schools, colleges, hospitals and residential building.
B. Heavy duty floor tiles
Used for heavy traffic conditions such as foot paths, entrances and staircase of public buildings, passeges or auditoriums and storage godowns.
Materials used
1. Cement
Cement used in the manufacture of tiles shall be ordinary Portland cement conforming to I.S. 269 – 1976 or rapid hardening Portland cement conforming to I.S. 8041 – 1978 or white Portland cement conforming to I.S. 8042 – 1978 or Portland I.S. 1489 – 1976
2. Aggregates
Aggregates used in the backing layer of tiles shall conform to the requirement of I.S. 383 – 1970 for the wearing layer unless otherwise specified aggregates shall consists marble chips of similar characterstics and hardness, marble powder or dolomite powder or a mixture of the both.
3. Pigment
Pigment, synthetic or otherwise used for flooring tiles shall have durable colour. If shall not contain matter determental to concrete and shall according to the colour required to one of the following or their combination.
Product and its uses
Mosaic floor tiles which are known as terrazzo tiles are made of cement concrete and colored stone chips. These are very attractive and colorful with smooth shining surface. These are extensively used for flooring purpose in building and commercial complexes. These are hard bearing termite proof inpemeable and easily cleanable.
Market potential
In view of growing building construction activity in rural and metropolitan cities throughout the country the demand for this mosaic tiles is ever increasing day by day therefore there is good scope for the creation of additional capacity by setting up new units in this line of manufacture in any part of the country.
Dimensions
The size of cement concrete flooring tiles shall be as
Length mm | Breath mm | Thickness mm |
250 | 250 | 20 |
250 | 250 | 20 |
250 | 250 | 20 |
Special shape and size
Shape and sizes of tiles other than those specified above may be manufactured when agreed upon between the supplier and purchaser provided that the tiles meet all the requirements of the standard.
General qualities
The tiles shall be supplied with initial grinding and grouting of the wearing layer. The wearing layer of the tiles shall be free from projection impression, cracks, holes, cavities and other blemishes. The edges of the wearing layer may be rounded.
Finishing
The colour and texture of the wearing layer shall be uniform throughout its thickness. No appreable difference of aggregate its type and is distribution on the surface of the wearing layer shall be present.
When indenting for terrazzo tiles the purchase shall state the size of chips to be used in the wearing layer.
Physical requirements
Flatness of the tiles surface
The tiles when tested according to the procedure laid down in Appendix A the amount of concavity and convexity shall not exceed 1 mm.
Perpendicularity
When tested in accordance with the procedure laid down in Appendix B, the longest gap between the arm of the square and the edge of the tile shall not exceed 2 % of the length of the edge.
Straightness
When tested according to the procedure laid down in the gap between the thread and the plane of the tiles shall not exceed 1% of the length of the edge.
Water absorption
When tested according to the procedure laid down, the average percentage of water absorption shall not exceed 10 %.
Wet transverse strength
When tested according to the procedure laid down the average wet transverse strength shall not be less than 3 N/mm2
Resistance to wear
When tested in the manner specified the wear shall not exceed the following value.
a) For general purpose tiles
1) Average wear 3.5 mm
2) Wear on individual specimen 4.0 mm
b) For heavy duty floor tiles
1) Average wear 2.0 mm
2) Wear on individual specimen 2.5 mm
Manufacturing process
The process for the manufacture of mosaic tiles consists of two layer the facing and the backing layers. The mixtures for those layers are prepared and stared in compartment provided in this work tables on the both sides of the hydraulic process ratio of the cement and coloured stone chips in the facing mixture varies from 1:15 to 1:5 and the proportion of sand and grey cement in the backing mixtures is 3:9. The mixture content of the these mixture differ from each other. The facing mixture should be in the form of slurry where as the backing mixtures in the damp condition.
Four moulds are provided to four workmen who are engaged to workdone one process one after another. The steel mould fitted up with bottom plate is filled in first with facing mixture by means of a ladle to a depth of ¼ “ and over it moist backing mixtures are spread out upto an over all thickness exceeding ¾ “ the top portion is lowered down and mixture is subjected to a pressure approximately 2000lbs per sq.inch and the final thickness of pressed tile generally brought down to ¾ “.
After withdrawing the moulds from the press the tiles are % removed and stocked in a wooden rack fitted with handles on both sides where they are allowed to remain for about a day, the tiles are taken to task where they are submerged under water for about 48 hours. After removing from the tanks the tiles are kept under a curing shed for about two weeks by spraying water every day, when the tiles are semi-polished in disc super levelling machines.
Points to be noted in manufacturing process
- Cement flooring tiles shall be manufactured from a mixture of cement, natural aggregates and colouring material where required by pressure process. Puring manufacture the tiles shall be subjected to a pressure of not less than 14 N/mm2
- The proportion of cement aggregates in backing of the tiles shall be not leaner than 1:3 by mass.
- Where colouring material is used in the wearing layer it shall be exceed to 10 % by mass of cement used.
- On removed from the mould, the tiles shall be kept in moist condition continuously for a such period that would ensure their confirmity to the requirements of this standard. Tiles shall be stored under cover.
