AIM
To determine the breaking load of clay roofing tiles (Mangalore pattern)
APPARATUS
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 weights and a received pan. The load shots flow through a supply pipe 950 in to the receiving pan.
The pan can be removed by just taking out a pin for transferring the load 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 steps. 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.
The 40mm diameter rolled 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 270 mm for 320 mm is attached to the loading yoke. The roller can be adjusted to slit centrally on the specimen while loading.
The load is applied to the specimen by allowing the load shout to flow into the receiving pan (loading pan) through a supply pipe with value. 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 shouts. Twelve times the weight of lead shots collected in the receiving pan gives the failure load. The counter balancing weight slides on the screw of the lower and can be locked in position by two nets after balancing the lever. A stop is provided to restrict the movement of lower lever when the specimen fails.
SPECIMEN
Three tiles should be used for this test from the sample selected.
PROCEDURE
(i) Put the counter balance weight on the screw attached to the lower lever.
(ii) Adjust the loading roller along with the yoke for the specimen thickness.
(iii) Adjust the counter weight so that the lower lever is in balanced position.
(iv) Keep the bearing roller at the proper centre distance according to the specimen tested.
(v) Keep the specimen on the bearing rollers.
(vi) Adjust the loading roller so that the loading roller is in contact with the specimen.
(vii) Start loading the specimen by starting the flow of 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 closes the flow of lead shots.
(viii) Remove the loading pan
(ix) Weigh the lead shots collected in the pan on a balance.
(x) Multiply this weight by twelve to get the actual load at which the specimen failed.
NOTE
Keep three tiles in water at 27 ± 2°C for 24 hours. And test them in wet condition and three tiles in dry condition. Support the tiles evenly flat-wise on bearers set with a sp-an of 27 cm and resting on bottom surface. Apply load with the direction of the load perpendicular to the span at a uniform rate 25 to 55 kg/min.
RESULT
Breaking load of tile in wet condition =
Breaking load of tile in dry condition =
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