EU Norm (EN459)Summary of Terminology for Building Limes
|Hardening only in contact with CO2 in the air (Carbonation) Classified according to their Calcium oxide/magnesium oxide content (90,85,80,70)|
Calcium Oxide + Magnesium Oxide
calcinated and producing an exothermic
reaction in contact with water
|CAEB||CL (calcium lime)||Calcium oxide or Calcium Hydroxide
|DL (dolomitic lime)
Semi hydrated and hydrated
|Calcium and Magnesium Oxides OR
Calcium and Magnesium Hydroxides
|Hydrated lime||CL or DL resulting from controlled slaking of quicklime. Produced as POWDER, PUTTY or SLURRY (milk of lime).|
Hydraulic Lime - Setting and hardening in contact with water. Air setting also present. Classified according to Compressive Strength expressed in N/mm2 measured @ 28 day in mortars prepared with a 1:1 binder/sand ratio
|OLD||NEW||Natural hydraulic lime (NHL)|
or XHN 100
|NHL 5||NATURAL HYDRAULIC LIMES
Argillaceous or siliceous limestone burnedand slaked . Reduced to powder with or without grinding.
NO ADDITION ALLOWED
or XHN 60
or XHN 30
|IF ADDITIONS OF SUITABLE POZZOLANIC OR HYDRAULIC MATERIALS (up to 20%) ARE MADE THE ABOVE PRODUCTS MUST BEAR THE DESIGNATION OF NHL-Z|
|ARTIFICIAL HYDRAULIC LIME
|A blend of calcium hydroxide, calcium silicate and calcium aluminates (and possibly othermaterials such as ash, fillers etc… N.D.R.)|
NOTES: Artificial hydraulic limes (HL) are not regulated in their overall composition and the presence of cement is almost certain. A more appropriate definition would have been HB (Hydraulic Binders) instead of HL. Should be avoided in restoration and conservation work. The addition permitted in NHL-Z of up to 20% of other materials in conjunction with the further allowances made in the Norm related to the presence of SO3 (3% AND UP TO 7% subject to soundness test) and the small amount of Available Lime required in NHL products (3% -15%)* can cause problems. These additions will consist of cement or other materials (i.e. Gypsum) used in order to achieve constancy in the performance of otherwise unreliable products. Although in many instances this will be acceptable in new build, in restoration and conservation work.
NHL - Z products could produce unwanted effects.
* Available lime in St. Astier NHL products: from 20% to over 50%.
For further Guidance, contact your St Astier Distributor.