FUNCTIONS OF INGREDIENTS OF MORTAR

As discussed earlier, the ingredients of mortar are:

1. Binding or cementing materials, viz., cement or lime
2. Fine aggregates, viz., sand, surkhi, cinder, etc.
3. Water

7.4.1 Functions of Cementing Materials

The primary requirement of cementing materials is to provide strength and durability to the structure.

For cement mortar mostly Ordinary Portland Cement is used. However, for special types of works other cements may be used appropriate to the work. Cement performs the following functions when used in cement mortar:

1. Primarily, it fills the voids formed by fine aggregates and thereby makes the mortar impermeable.
2. It binds the fine aggregates into a solid mass with time on adding water to the mix.
3. It imparts strength after setting and hardening.

For lime mortar, different types of lime are used, viz., eminently hydraulic, semi-hydraulic and fat limes. For preparing lime mortar, the lime should be slaked before mixing it with the fine aggregate. However, the strength of lime mortar is less than that of cement mortar. Lime performs the following functions when used in lime mortar:

1. It binds the fine aggregates into a solid mass. However, it takes more time to set.
2. It imparts adequate strength to the lime mortar on setting and hardening.