Tests on Lime

TESTS ON LIME

To determine their suitability, the following tests are conducted on lime:

Physical Test:

Physical test is conducted to examine the physical properties of lime. The physical properties of lime can be estimated by its color, smell, texture, etc. White color indicates pure limestone. Hydraulic limestones are bluish grey, brown or are having dark colours. Hydraulic limestone tastes like clay and produces an earthy smell. Similarly, the presence of bulges or bumps indicates it as quick lime. If limestone is glittering or shining, then it indicates the presence of free salts in it.

Chemical Test:

Chemical test is used to determine the amount of calcium carbonate and type of lime present in the limestone. The procedure for chemical test is as follows:

❖ In a test tube, a teaspoon full of powdered lime is taken and 10 ml of dilute hydrochloric acid is added to it.

❖ It is stirred thoroughly and the mix is kept in a safe place for 24 hours.

❖ After 24 hours, the mix should be observed. If there is a formation of high effervescence and fewer residues are left at the bottom of the tube, then it indicates a high amount of calcium carbonate which represents pure limestone.

❖ If the formation of effervescence is less and more residues are left at the bottom of the test tube then it indicates less amount of calcium carbonate in it and is treated as impure or hydraulic limestone.

❖ To classify the lime present in the limestone, another test is performed in continuance to the above test.

❖ In this test, the above test tube is inverted upside-down. If the gel formed above the residue is not moving even when the test tube is inverted then it is designated as class A lime.

❖ If the gel formed tends to flow when the test tube is inverted then it is designated as Class B lime.

❖ If there is no gel formation, then it is designated as class C lime.

Heat Test:

Heat test is performed to find the amount of calcium oxide (lime) present in the limestone. The test procedure is as follows:

❖ In this test, a sample of dry limestone is weighed (W₁) and it is heated for four hours in an open fire.

❖ During heating, CO₂ present in the limestone evaporates and weight reduces (W₂) and is recorded.

❖ Form this weighed data W₂- W₁, amount of calcium oxide content present is determined.

Ball Test:

This test is conducted to categorize whether the lime belongs to class B or C. The test procedure of ball test is as follows:

❖ Small quantity of powdered lime is taken and little water is added to it until stiff consistency is obtained.

❖ Using this stiff mixture, balls of 40 mm size are prepared and are left undisturbed for 6 hours. 08.1 vileuen

❖ After 6 hours, the balls are immersed in a water basin and results are observed. Ilam?

❖ If there is no expansion or very little expansion and numerous cracks on balls then it indicates the presence of class B lime.

❖ If lime balls are expanded and disintegrated in the water within minutes then it indicates the presence of class C lime.