Correct Answer - Option 4 : Fat lime
Explanation:
Different types of lime:
Fat lime:
(i) This lime slakes vigorously due to which its volume increases by 2 to 2.5 times than its original volume. Hence it is referred to as fat lime.
(ii) It posses a perfectly white colour, hence also termed as white lime.
(iii) It is obtained by the calcination of limestone of approx. 95% purity, hence it is also referred to as pure lime, rich lime, or highly caustic lime.
(iv) Its properties are:
- It hardness very slowly with vigorous slaking.
- It has good solubility in water
- It possesses a high degree of plasticity.
- In the presence of air, it sets slowly.
- Fat lime is mostly used for plastering and whitewashing.
Hydraulic lime:
(i) It is also referred to as water lime as it is capable of setting in water and in damp locations.
(ii) It is obtained by the calcination of limestone having the purity in the range of 70 - 92%.
(iii) It is insoluble in water and possesses off-white colour.
(iv) Its hardness is comparatively faster than fat lime, hence is used in engineering works where strength is required. Ex: Brick masonry and stone masonry.
Poor lime:
(i) It is also referred to as impure lime or lean lime as it is obtained from the calcination of limestone having a purity of less than 70%.
(ii) This lime does not undergo slaking, hardness very slowly, possess muddy white colour, hence is used in Engineering works of minor importance. Ex: Brickwork around the foundation.
