Durability Test On Stones
What is Durability?
- Durability is the ability of a material to resist changes in its properties.
- The durability of a stone depends upon its composition, which can affect its strength, appearance and environmental exposure factors.
Why durability test is performed on stones?
- The durability test on stones is performed to estimate their capacity to resist disintegration and decomposition.
- There is a requirement for performing this test as a poor durability stone can result in diminished building appearance, may require supplemental repairs to address deterioration, or in extreme cases may require replacement of panels or entire facades.
- The durability test on stones can result in significant savings in the future.
|Durability Test On Stones|
So, the tests which fall under the category of durability test on stones are as follows:-
- This test is used to check the presence of soluble matter in the stone.
- Break off the freshly quarried stone chippings to about the size of a rupee coin.
- Put them in a glass of clean water(one-third full).
- If the water becomes cloudy(or slightly cloudy), it indicates that the stone is good and durable.
- If the water becomes dirty, it indicates that the stone contains too many soluble impurities(or earthy and mineral matter) and it's not durable.
- This test is used to check the frost resistance in the stone.
- Few small pieces of freshly quarried stone are immersed in the boiling solution of Sodium Sulfate(Glauber's Salt).
- Then, these are removed and kept suspended for a few days in the air.
- The salt crystallizes in the pores of the stone, sometimes forcing off bits from the corners and edges, and occasionally detaching larger fragments from the stone.
- These small pieces of stone are weighed before and after submitting them to the test.
- The loss in weight indicates the effect of frost and gives the amount detached by disintegration from them.
- The greater the loss in weight, the lesser the durability of the stone.
- This test is used to check the weather resistance in the stone.
- It confirms the power of stones to withstand the atmospheric conditions.
- This test is also used to test the cementing material of sandstone.
- 100 grams of stone chips are kept in 5% solution of Hydrochloric acid or Sulphuric acid for 3 days.
- Then the chips are taken out and dried.
- If the edges and corners of these chips are sharp and firm as earlier, it indicates that the stone can resist weather conditions(or weathering actions) and it further indicates that the stone is durable.
- If the edges and corners of these chips get converted into curves then it indicates that the stone cannot resist weather conditions(or weathering actions) and is not durable.
- This test is used to check the durability or the weathering quality of the stone.
- Three test pieces of 50 mm diameter and 50 mm height are dried for 24 hours and are weighed(W1).
- The specimens are suspended in 14% Sodium Sulfate solution(of density 1.055 kg/m3) for 16 to 18 hours at room temperature(20° to 30°C).
- The specimens are then taken out of the solution and kept in the air for 4 hours.
- They are then oven-dried at a temperature of 105° ± 5°C for 24 hours and then cooled at room temperature.
- This process is repeated for 30 cycles.
- The specimens are then weighed (W2) and the difference in weight is found.
- This test is repeated 30 times and the loss in weight after every five cycles are obtained.
- The change in weight indicates the degree of decay of stone.
- Durability should be expressed in percentage as the change in weight.
- The average of three test results should be reported as durability value.
- Change in weight = (W1-W2)/W1
- Percentage wear= [(W1-W2)/W1]*100
- where W1 is the original weight of the specimen and W2 is the weight of the specimen after 30 cycles of the test.
- The percentage of wear should not exceed 2% for a good stone.
*Source- Internet, Books and Self-Analysis