Hydraulic lime
Types:
– Natural hydraulic lime (NHL) is produced by heating limestone naturally containing clay and impurities.
– In the United States, NHL may be called hydrated hydraulic lime (HHL) per ASTM C-141.
– Artificial hydraulic lime (AHL) becomes hydraulic by adding materials before or after burning.
– Formulated lime (FL) consists mainly of hydrated lime with added materials like Portland cement.
– Pozzolanic hydraulic lime (PHL) consists mainly of hydrated lime with pozzolans and possible inert filler.
Characteristics:
– Hydraulic lime has a low elastic modulus.
– Buildings using hydraulic lime do not need expansion joints.
– Lime allows buildings to breathe and prevents moisture trapping.
– It has a lower firing temperature than Portland cement, consuming less energy.
– Lime re-absorbs carbon dioxide emitted during its calcination process.
Hydraulic lime concrete:
– Hydraulic lime concretes have been used since Roman times.
– Lime can be used in a variety of applications due to its versatility.
– The Pantheon in Rome is an example of the longevity of lime concrete.
– Lime mixes can be adjusted to change properties and lightness of the material.
– Lime concrete can be used for floors, vaults, and domes.
Classification:
– Feebly hydraulic lime (NHL 2) is used for internal and sheltered external work.
– Moderately hydraulic lime (NHL 3.5) is suitable for most external work.
– Eminently hydraulic lime (NHL 5) is used for exposed areas like chimneys and floor slabs.
– These classifications are based on the amount of clay present in the lime.
– Properties of eminently hydraulic lime are similar to cement.
Benefits:
– Hydraulic limes gain strength over time, avoiding the need for expansion joints.
– They are considered more environmentally friendly than Portland cement.
– Hydraulic lime enables reclamation and reuse of building components.
– It can set under water, making it suitable for applications in contact with water bodies.
– The unique properties of hydraulic lime make it ideal for various construction applications.https://en.wikipedia.org/wiki/Hydraulic_lime