Field Testing of Building Lime for Quality in Construction Works
Neenu S K
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Different types of field tests on building lime to check the quality of lime to be used in mortar mix for construction works and their procedures are discussed.
Tests on building lime can be carried out as field tests or as laboratory tests. The detailed laboratory tests on building lime as per IS 6932 – 1973 is discussed in another article.
Simple field tests on building lime helps to define the quality of lime when it is directly bought from the kiln. Mainly the field tests are used to test the quality lime in the form of quicklime i.e. calcium oxide (CaO).
The industrial consumers demand minimum lime content. If 60 % of calcium oxide for hydrated lime is the minimum requirement means that nearly 80% is the maximum that is possible. In situations where lime is used for chemical stabilization, in road making, it is the impurities in chemical means, in the form of lime that is important.
Samples for Physical Tests on Building Lime
The test samples that is required to conduct the physical test must be collected as fast as possible before it starts to deteriorate. To carry out the test for quicklime and for hydraulic lime, from each lot, 3 samples were taken.
The sample size that is recommended for quicklime is given in table-1. For tests on hydraulic lime, the weight should not be lesser than 5kg.
Table-1: The Sample Size for Physical Test for Building Lime
Lot Size, Tonne
Gross Sample Size for Lump Quicklime, Kg
Gross Sample Size for Powdered Quicklime, Kg
Up to 100
500
250
101 to 300
1000
500
301 to 500
1500
750
501 to 1000
2000
1000
Field Tests on Building Limefor Construction Works
The IS 1624-1974 specifies certain field tests on building lime. These are:
1. Visual Examination
The class C lime, will have white color under visual examination
2. Hydrochloric Acid Test
The powdered lime (leveled teaspoon of lime) is taken in a test tube (the quantity will be almost 10cc). To this hydrochloric acid is poured, till the efflorescence ceases. It is kept to stand for 24 hours. The bubbling action of the reaction shows the presence of lime. The insoluble residue in the same shows the presence of inert material (Phenomenon named as adulteration).
After 24 hours, a thick gel is formed. If the gel has no kind of flowing capability; It is actually a representation of the presence of class A lime. If the gel has a flowing capability, it is Class B lime. If no kind of gel is formed, the presence of Class C lime is fixed.
3. Ball Test
With the addition of water to lime, a ball shape with lime is made. It is placed in a basin of water after storing it for 6 hours. If after placing in water, any kind of disintegration is seen within few minutes, the Class C lime presence is found.
If a little expansion is found, with some number of cracks within it, the Class B lime is detected. If no kind of adverse effect on the ball is found, Class A lime is detected.
4. Impurity Test on Building Lime
Lime of known quantity is taken in a beaker and mixed with water. The solution is then let to transfer. The obtained residue is allowed to dry under the sun for a time period of 8 hours after which, it is dried.
If the residue is less than 10 % in amount, then the lime is good. If it is between 10 to 20 %, the lime can be considered fair. Above 20%, the lime is regarded poor or impure.
5. Plasticity Test on Building Lime
The lime is made into a thick paste with sufficient quantity of water. The sample is left overnight. The next day it is laid over a blotting paper, by means of a knife. This way the plasticity of the lime is checked. A good lime is considered plastic in nature.
