Maawa World

LIME MORTAR Fat lime and hydraulic limes are used for making lime mortar. If fat lime is used sand mixed is normally 2 to 3 times its volume. If hydraulic lime is used sand mixed is only 2 times the volume of lime. Lime is prepared by pounding, if quantity required is small or by grinding, if the required quantity is more.   Pounding: For pounding pits are formed in hard grands. The size of pit is usually 1.80 m long, 0.4 m wide and 0.5 m deep. It is provided with lining of bricks or stones. Lime and sand dry mixed with required proportion is placed in the pit. Small quantity of water is added at intervals. In each interval the mix is pounded with wooden pounders and mortar is turned up and down. The process is continued till uniform colour and desired consistancy is achieved. Grinding:  This is the better way of getting good mix. The grinding may be carried out in bullock driven grinding mill or in power driven grinding mill. A typical bullock driven grinding mill. It co

CEMENT MORTAR For preparing mortar, first a mixture of cement and sand is made thoroughly mixing them in dry condition. Water is gradually added and mixed with shovels. The cement to sand proportion recommended for various works is as shown is Table. Table, Cement to sand proportions for various works S. No.                Works                Cement: Sand   1               Masonry works            1:6 to 1:8   2             Plastering masonry       1:3 to 1:4   3             Plastering concrete            1:3   4                      Pointing                 1:2 to 1:3 Curing: Cement gains the strength gradually with hydration. Hence it is necessary to see that mortar is wet till hydration has taken place. The process to ensure sufficient moisture for hydration after laying mortar/concrete is called curing. Curing is ensured by spraying water. Curing normally starts 6–24 hours after mortar is used. It may be noted that in the initial period water requirement is more fo

SAND Sand is a natural product which is obtained as river sand, nalla sand and pit sand. However sea sand should not be used for the following reasons: 1. It contains salt and hence structure will remain damp. The mortar is affected by efflorenscence and blisters appear. 2. It contains shells and other organic matter, which decompose after some time, reducing the life of the mortar. Sand may be obtained artificially by crushing hard stones. Usually artificial sand is obtained as a by-product while crushing stones to get jelly (coarse aggregate). Sand is used in mortar and concrete for the following purpose: 1. It sub-divides the paste of binding material into thin films and allows it to adhere and spread. 2. It fills up the gap between the building blocks and spreads the binding material. 3. It adds to the density of the mortar. 4. It prevents the shrinkage of the cementing material. 5. It allows carbon dioxide from the atmosphere to reach some depth and thereby improve

Mortars Mortar is an intimate mixture of binding material, fine aggregate and water. When water is added to the dry mixture of binding material and the inert material, binding material develops the property that binds not only the inert material but also the surrounding stones and bricks. If the cement is the binding material, then the mortar is known as cement mortar. Other mortars commonly used are lime mortar and mud mortar. The inert material used is sand. In this chapter, first an introduction is given to the inert material sand and then the proportioning, mixing, curing, properties and uses of different mortars is explained. At the end of the chapter various tests conducted on mortars is presented.