Tile is a square-rectangular thin unit which is manufactured from natural stone, ceramic, baked clay, glass, metal, terrazzo, and quartz. Each type of tile possesses certain characteristics and they are selected to cover floors based on their strength, aesthetics, cost etc.
The transverse strength of tile is one of the requirements that to be satisfied. It is a numerical representation of how much weight a tile can support. Transverse strength test, which wet and dry test, is conducted in to estimate tile breaking load. The tile strength would determine the type of application the tile is appropriate for.
The tile testing machine consists of an angle iron frame. A double lever system is provided for applying the load. The lower lever is supported on a bearing and carries a weight and a receiving pan.
The lead shots flow through a supply in to the receiving pan. The pan can be removed by just taking out a pin for transferring the lead shot to the storage pan. The storage pan is permanently fixed through the top plate.
The upper lever is connected to the lower lever by means of straps. The upper lever is held by an adjustable capstan. The adjustable loading yoke is connected to the upper lever through the vertical rods passing through the top plate. The loading yoke cross head can be locked in position after mounting the specimen.
Three 40 mm diameter rollers are provided. The self-aligning bearing rollers are mounted on the metal blocks. The guide pins are fixed to the block and the corresponding holes are drilled on the top plate to adjust the center distance of bearing rollers to 250mm and 270mm for 320mm and 345mm long tiles respectively.
The third rolling roller, also of 40mm diameter is attached to the loading yoke. The roller can be adjusted to sit centrally on the specimen while loading.
The load is applied to the specimen by allowing the lead shots to flow into the receiving pan(loading pan) through a supply pipe with a valve. The orifice of the valves is adjusted to load the specimen at the rate of 45- 55 Kg/min.
An L-shaped plate is attached to the lower , which would strike automatically on the shutter of the valve as soon as the specimen fails, thereby cutting the flow of lead shots. Twelve times the weight of lead shot collected in the receiving pan gives the failure load.
The counterbalancing weight slides on the screw of the lower and can be locked in position by two nuts after balancing the lever. A stop is provided to restrict the movement of the lower lever when the specimen fails.
A total of six tiles shall be tested for dry strength and six tiles should be tested for wet strength.
Put the counter balance weight on the screw attached to the lower lever. Adjust the loading roller along with the yoke for the specimen thickness. Adjust the counter weight so that the lower lever is in balance position.
Keeping the specimen on the loading rollers, start loading the specimen by starting the flow of the lead shots. For this, the shutter lever by pressing it down. As soon as the specimen fails the lever strikes hard on the shutter and close the flow of lead shots.
Dry Test Procedure
- Place the tile specimen(air dried) horizontally on bearers with its wearing surface uppermost and its sides parallel to the bearers.
- Place a plywood packing 3mm thick and 25mm wide between the tile and the bearers and also between the tile and the loading bar.
- Apply load to the mid-span starting from zero and increase it steadily and uniformly at a rate not exceeding 200kg per meter width(measured along the bearer) per minute until the specimen fails.
- Note the breaking load.
- Repeat the experiment on the remaining tile specimens also and take the average.
Wet Test Procedure
- Immerse the tile specimens in water for 24 hours.
- Take out the specimen from water and wipe to dryness.
- Test the specimen as described in the dry test.
Breaking load due to dry test and breaking load due to wet test are recorded. The transverse strength can be computed from the following equation:
P: breaking load, N
I: span between supports, mm, see Table 1.
b: tile width, mm
t: tile thickness, mm
Table 1 designated span for tiles to be tested for transfer strength
|Size of tile, mm||Span, mm|