To determine the breaking load of Terrazo flooring tiles
The tile testing machine
The unit consists of an angle iron frame. A double lever system with a ratio 1:12 provided for applying the load . The lower lever is supported on ball bearing and carries a counter balanced 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 centre distance of bearing rollers to 250mm and 270mm for 320mm and 345mm long tiles respectively. The third rolling roller, also of 40mm 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 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 lever, which will strike automatically on the shutter of the valve as soon as the specimen fails, there by cutting the flow of lead shots. Twelve times the weight of leadshot collected in the receiving pan gives the failure load. The counter balancing weight slides on the screw of the lower lever and can be locked in position by two nuts after balancing the lever . A stop is provided to restrict the movement of lower lever when the specimen fails.
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 operate 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 leadshots.
Full size tiles – 6 No’s.
1. Dry Test for Transverse Strength
(I) Place the tile specimen (air dried) horizontally on bearers with its wearing surface uppermost and its sides parallel to the bearers.
(II) Place a plywood packing 3mm thick and 25mm wide between the tile and the bearers and also between the tile and the loading bar.
(III) Apply load to mid-span starting from zero and increase it steadily and uniformly at a rate not exceeding 200kg per metre width (measured along the bearer) per minute until the specimen fails.
(IV) Note the breaking load.
(V) Repeat the experiment on the remaining tile specimens also and take the average.
2. Wet Test for Transverse Strength.
- Immerse the tile specimens in water for 24 hours.
2. Take out the specimen from water and wipe to dryness.
3. Test the specimen as described in the dry test.
Six tiles should be tested for dry strength and six tiles should be tested for wet strength
Breaking load (dry test) =
Breaking load (Wet test) =