Lime mortar is made of lime and an aggregate such as sand, which is mixed with water, Ancient Indians first used lime mortar for plaster temples.
It is primarily used in the conservation of buildings initially constructed using lime mortar, however, it may be used as a substitute for ordinary Portland cement.
These qualities lead to initial deterioration of soft and old bricks, usually low temperature fired, lime mortars are recommended to be used.
Properties of Lime Mortar:
- This mortar is relatively plastic and workable when it is wet.
- It has good working properties if made from excessive calcium lime.
- It develops the strength very slowly however achieve strength constantly for a very long time.
- Also, does not set however it harden, when water is lost by absorption and evaporation by the blocks.
- It provides a fairly strong surface, when used for plastering.
- It provides the adequate bonding, when used for masonry joints.
Types of Lime Mortar:
1.Hydraulic Lime Mortar:
This mortar is made with Natural Hydraulic Lime (NHL).
It has excellent stability of power and flexibility, available in a variety of strengths to garb absolutely different applications.
It sets in damp conditions and soon reaches a power preventing frost damage.
On the similar time, it remains softer and sympathetic to the masonry when absolutely cured.
The material is available in powdered form like a modern cement mortar to combine and it is also the most tolerant of the unconfirmed.
2.Non-Hydraulic Lime Mortar:
This mortar is made with non-hydraulic lime, usually referred to as lime putty.
This mortar is extra soft and versatile, perfect for the conservation of gentle masonry.
It carbonates very slowly, however it leaves frost damage in cold conditions and it is not suitable for damp conditions.
The material offered as a moist, pre-mixed mortar that is practically unlimited if saved properly.
3.Hot Mixed Lime Mortar:
This mortar is made with quicklime, lots of heat is produced throughout mixing.
This sticky, lime-rich mortar is most popular in constructing preservationists as scorching mixing however, non-hydraulic lime mortars have a low resistance to frost.
The material is offered as a moist, pre-mixed mortar though it is typically assisted in cold and aged.
A pozzolana will be added an “air lime” mortars to make hydraulic setting characteristics.
A preliminary hydraulic set drives initial strength and it can introduce some frost resistance in non-hydraulic and hot-mixed lime mortars.
Advantages of Lime Mortar:
- It reduces the need for movement joints.
- Makes use of much less energy to produce than cement.
- Re-absorbs the CO₂ when it cures and sets.
- It also permits masonry to be recycled at the finish of life.
- It provides a breathable type of construction.
- Also provides a water-shedding barrier for walls.
- It enhances brickwork and various masonry.
- This mortar has constant prime quality and color of the mortar.
- These mortars might be re-worked for up to 24 hours.
- Also reduces wastage when using a silo structure.
Disadvantages of Lime Mortar:
- Quick setting time limits the time obtainable.
- Some cement contains appreciable quantities of soluble salts, particularly potassium sulfate which may become a supply of salt loss to the stonework.
- The use of cement leads the consumer to deal with gold lime mortars as it has been purely hydraulic lime or cement.
- An excessive amount of initial chemical set ignores the importance of extended carbonation of the non-hydraulic component.
- There is a risk of separation causing the cement to separate from the lime because the mortars dry and hardens.
Uses of lime mortar:
- Fats lime mortars can be used in all types of foundation work that is in dry subgrade i.e. water table 2.4 meters under the foundation level.
- Fats lime and hydraulic lime are both appropriate for all masonry works.
- Lime mortars could be replaced with cement mortars.
- Additionally used to bind stones, bricks, or concrete blocks together.
- Lime mortars cannot be used when the subgrade soil is moist or the water table is within 2.4 m.
- Heavy loading is expected.
- The construction is very large and very rough.
Also read: Types of lime, Types of mortar & Lime plaster
Natural lime mortar is flexible, thus allowing movement into the building and prevents cracks in the masonry.
In addition, they are breathable (vapor permeable), drawing the vapor present in the masonry back into the air.