Natural hydraulic limes set even when wet and come in a range of strengths. They are useful for building with stone or brick where the earlier set may speed up construction. You can also add a pozzolan such as metastar to a lime putty mortar. We suggest that for external bedding and pointing late in the year natural hydraulic lime should be used. It is capable of a faster initial set in cold weather.

This is made from limestone that contains impurities such as clay or silicates. Unlike lime putty which is non-hydraulic lime, NHLs can set in damp conditions. They also have some free lime available for carbonation. There are three European classifications NHL 2, NHL3.5 and NHL5 based on the compressive strength of laboratory mortars after 28 days. These are often somewhat misleadingly termed feebly hydraulic, moderately hydraulic and eminently hydraulic.

Hydraulic lime mortar is a lime mortar that hardens in damp or even wet conditions through a chemical reaction rather than exposure to air. (This is in contrast to standard, or non-hydraulic lime mortars, which harden by absorbing carbon dioxide, a process known as carbonation.) Hydraulic qualities are created when clay is included in the lime mixture.

No there is full range of lime mortars with different strengths and degrees of resistance to damp conditions. You should choose the right one, bearing in mind the exposure of the wall, the location of the property and the condition of the stone or brickwork that you are repairing, rendering or re-pointing. If you require specific free advice on appropriate mixes please contact us or read our technical sheets.

Lime is calcium oxide applied in granular form. Lime helps improve lawn color and density, controls thatch, and increases root development. Lime balances the pH levels in the soil that have been affected by the fertilizer applications throughout the year. To read more about the importance of Lime, please read our Article entitled "Winter Care."

What are the standard tests used to determine the percent of available lime (CaO%) and how do they differ? (ASTM C25 and AWWA B202 standard tests) Why is sugar added when running the standard titration for the percent of available lime (CaO%)? (ASTM C25 and AWWA B202 standard tests)

Spalled brick in an1860s lighthouse that was repointed with portland cement mortar about twenty years ago. The historic stone masonry units have deteriorated dramatically, while the portland cement mortar joints remain intact. It' s important to understand that historic buildings are very different than modern buildings in several key ways: First, historic brick--in particular--is softer than modern brick because modern brick is fired at a much higher temperature than was possible in the past.

Either. Pelletized is easier to apply but powder is cheaper. Use powder if you intend to incorporate. There is no difference in speed of reaction.

A lime render is a coating of lime-based material that was traditionally applied over rough, unsightly brickwork or rubblestone masonry walls. Non-hydraulic lime stuccos and hydraulic lime stuccos are common lime-based renders. In addition to these traditional applications, lime renders can restore some measure of protection to masonry buildings that have been sandblasted. (Sandblasting a masonry building is incredibly damaging.

Yes. As we have already mentioned on this page, historic brick was fired at a lower temperature and is typically softer than modern brick. Construction techniques have changed, but it's still important that the mortar accomodate the historic brick. Due to the prevalence of portland cement mortars (notably the standard Type N), very few masons have worked with traditional lime mortars.

ASTM has Standard Methods for testing chemical (C25) and physical (C110) properties. These standards can be purchased directly from ASTM at www.astm.org.

Hydrated lime can be used to raise the pH of acidic soils. This is also referred to as soil "sweetening." Hydrated lime is available from garden centers and should be applied in the amounts and using the procedures recommended on the packaging.

P. Mold & R. Godbey. "Limewash - Compatible Coverings for Masonry & Stucco." 2005, International Building Lime Symposium Proceedings (ISBN 0-9767621-0-2). R. Bennett. "The Use of Limewash as a Decorative and Protective Coating." The Building Conservation Directory, 1997, pp. 136-137. British] Quarry Products Association (formerly the British Quarry and Slag Federation). "Lime in Building." 1974.

There are a wide range of different lime mortars available, all with different characteristics, and suitable for different applications. Non-hydraulic limes (CL90) are commonly available as 'lime putty', in 25kg bags or by the tonne. Natural Hydraulic Limes (NHL) Mortars are commonly available in 25kg bags from a wide range of manufacturers. NHL's come in a range of classifications based on compressive strength in N/mm2 at 28 days: NHL 2, NHL 3.5 & NHL 5.

Before this century building techniques and materials were very different from those employed today. Traditional properties need to "breathe" to allow moisture inherent in a solid wall construction without a damp proof course to evaporate from the external stonework or render. Many old buildings are constructed from materials such as brick, cob and stone which are relatively porous and often of lower strength. Lime mortars were normally used for bedding and plastering.

This is generally determined by the volume (tonnage) of lime used. A good way to think of quicklime is that it is hydrated lime without the water. It's important to understand that when water is added to quicklime it chemically combines with it to form two products: calcium oxide (quicklime) and carbon dioxide. The weight ratio is that 100 tons of pure calcium carbonate would ideally produce 56 tons of calcium oxide (quicklime).