When should you use lime mortar?

The use of a lime mortar for pointing in general masonry allows you to use a material that is both porous and softer compared with mortars that feature cement. This allows the moisture to evaporate from the joints more effectively which reduces the level of moisture in the fabric of the building.

What are the disadvantages of lime mortar?





DISADVANTAGES

  • the rapid setting time limits the time available to the user in which to work with the gauged mortar.
  • some cements contain appreciable amounts of soluble salts, in particular potassium sulphate, which may become a source of salt damage to stonework.

What does lime do to concrete?

Lime provides high water retention that allows for maximum early curing of the cementitious materials. High initial flow which permits easy complete coverage of masonry units. The low air content of cement-lime mortar increases bond strength.

What is the difference between lime mortar and cement mortar?

Lime mortar is more porous than cement mortars, and it wicks any dampness in the wall to the surface where it evaporates. Thus any salt content in the water crystallises on the lime, damaging the lime and thus saving the masonry.

How long will lime mortar last?

Most bagged, hydrated lime has a shelf life of 12 months once kept dry and sealed. Once opened bags should be used straight away or resealed so as to be airtight. Some premixed lime mortars with additives may have a shorter shelf life. Lime putty will last indefinitely once kept underwater and airtight.

Why is lime plaster no longer commonly used?





The promotion of modern gypsum-based plasters has led to the almost complete demise of lime plastering, and of many of the traditional skills associated with the craft. This has been exacerbated by the plastering trade being divided into flat and decorative work, with new ‘fibrous plasterwork’ being made in workshops.

Can you mix lime mortar with cement?

When mixing separate bags of cement and lime, hydrated lime must be completely wetted out in the mixing process or it will continue to absorb water after mixing. By following the proper mixing procedures, excellent board life, workability and sand carrying capacities are achieved with lime mortars.

What are the benefits of lime mortar?

Benefits of using lime in mortars and renders

  • Fresh properties: Improves workability and water retention. …
  • Hardened properties: Reduces potential for water penetration. …
  • Workability and water retention. …
  • Cracking and movement. …
  • Moisture movement, frost resistance and durability. …
  • Aesthetics. …
  • Hydrated lime. …
  • Hydraulic lime.

What is the correct mix for lime mortar?

The mix is typically 1 part lime : 2.5 parts sand. Measuring the material must always be with a gauging box or bucket. A shovel is not acceptable since quantities are too inconsistent. Lime mortars mixed in drum mixers can be prone to balling.

Which is better cement or lime?



Lime hardens much more slowly than cement-containing mortars, making it much more workable. Lime is also less brittle and less prone to cracking, and any cracked areas can absorb carbon dioxide and mend over time. Cement hardens very quickly, but may be too strong for some applications, e.g., working with old bricks.

Why does lime mortar crumble?

Crumbling or failing mortar can be caused by a number of reasons: Failing mortar can usually be attributed to a lack of carbonation of the lime within the mortar meaning that the mortar will have little if any, strength.

Is lime mortar waterproof?

Lime plaster is permeable and allows for the diffusion and evaporation of moisture. However, when properly worked with pozzolanic agents and animal fat, it becomes impermeable.

Can you lime plaster over cement?



There is no magic mix either, if it has cement in it, it is a cement based mortar, even if you add lime as a plasticiser. Re the wall. Cement will do the job and if the wall is in a good position, not damp, gets plenty of air and sunshine you might not have a problem.

Can I use lime mortar in winter?

The use of lime putty mortars externally during the winter months is not advocated, and certainly not when the temperature is below 5°C and falling. External work should be scheduled to avoid the period from October to March.

Is lime mortar breathable?

The pros and cons of using lime materials

Breathability – lime materials are highly breathable. Their vapour permeability means they allow water to pass through them, as either a gas or a liquid. This avoids the build-up of moisture, reducing the risk of damp or condensation.

Can you reuse old lime mortar?



Old lime mortar can be crushed and re-cycled as a soil conditioner to balance the pH of soils.

What is the difference between lime and hydrated lime?

The key difference between quicklime and hydrated lime is that the quicklime (or burnt lime) contains calcium oxide whereas the hydrated lime (slaked lime) contains calcium hydroxide. The major source for both quicklime and hydrated lime is the limestone. Therefore, like limestone, these compounds are also alkaline.

Should I use hydraulic lime or hydrated lime?

The more hydraulic a lime is, the faster it sets and the higher its final strength, but this means that it is less breathable and flexible.
Comparison table:

Hydraulic Lime Non-hydraulic Lime
Sets by hydration (the addition of water) Sets by carbonation (through exposure to the air)

What is the difference between lime mortar and lime plaster?

Whilst lime mortar is predominantly a building material, used to bind together masonry, lime plasters and renders need to be spreadable and may therefore contain more water and a finer aggregate.

What’s the difference between hydraulic and non hydraulic lime mortar?



Lime putty can be made from either type of lime, and is made by adding an excess of water to quicklime. Hydraulic lime putty will set underwater within hours or days making them impractical, whereas non-hydraulic lime putty will remain plastic and improve with age.