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Important mechanical properties of materials:- ELASTICITY:-  In this property body regains completely its original shape & size then it is called perfectly elastic body. Elastic limit marks the partial break down of elasticity beyond which removal of load result in degree of permanent deformation. Steel, aluminium, copper, may be considered to be perfectly elastic within certain limit   ·      Plasticity:- The characteristics of material by which it undergoes inelastic strain beyond those at the elastic limit is known as plasticity.   This property is particularly useful in operation of pressing and forging. When large deformation occurs in a ductile material loaded in plastic region, the material is said to undergo plastic flow. Ductility:- It is the property of material in which a material can be drown out longitudinally to a reduced section, under the action of tensile force.   A ductile material must possess a high degree of plasticity and strength. Ductile

  ·          Building mortar is define as a mixture of cement, sand and water. ·          Mortar is similar to concrete but it does not contain coarse aggregate. ·          Mortar are used for filing joints as a binder in stone and brick masonry   Bulking of sand ·          In the case of aggregates there is another effect of the presence of moisture viz. bulking which is an increase in the volume of a given sand particle apart. for a moisture content of about 5-8 % depending upon the   increase of volume may be as much as 20-40% depending upon the grading of sand . ·          Finer the materials more will be the increase in volume for a given moisture content. Classification of mortars ·          Mortars are classified on the basis of the following. (i)             Bulk density (ii)           Kind of binding materials (iii)          Naturals of application (iv)          Special mortars Properties of a good mortar The important properties of good mortar mix are mobility, place and wate