Understanding Mortars: Types, Bulk Density, And Applications

Mortars are essential in construction, and they can be classified based on several factors: bulk density, type of binding material, nature of applications, and special properties/mortar. Here’s a comprehensive look at these classifications.
Bulk Density
Heavy Mortars: Mortars with a bulk density of 15 kN/m³ or more. They are made from heavy quartz or other dense sands.
Lightweight Mortars: Mortars with a bulk density of less than 15 kN/m³. These are prepared from light, porous sands, pumice, and other fine aggregates.
2. Types Of Binding Material
The choice of binding material is crucial and depends on factors like working conditions and moisture levels. Mortars are classified into the following categories based on binding materials:

1. Lime Mortar:
Uses lime as the binding material, which can be either fat lime or hydraulic lime.

Fat lime shrinks to a great extent and hence it requires about 2-3 times its volume of sand.
Lime should be slaked before use.
Lime mortar is unsuitable for waterlogged areas or in damp situations.
For hydraulic lime, the proportion of lime to sand by volume is about 1:2.
Lime mortar has high plasticity and can be placed easily.
It shrinks very little.
It is sufficiently durable.
It hardens slowly
2. Surkhi Mortar:
Made by using fully burnt Surkhi (type of finely powdered burnt clay) instead of sand or replacing half the sand in fat lime mortar. It is used for ordinary masonry work in foundations and superstructures but is not suitable for plastering or pointing as it may disintegrate over time.

3. Cement Mortar:
Uses cement as the binding material. The proportion of cement to sand by volume varies from 1:2 to 1:6 or more, depending on strength requirements. It is ideal for high-strength and water-resistant applications like underground constructions and water-saturated soils.

4. Gauged Mortar:
A combination of lime and cement to improve quality and achieve early strength. The usual proportion of cement to lime