Astier NHL products for use with masonry cladding. |
For the purpose of this document Masonry Cladding means thin sections of masonry each one fixed back to a frame or substructure or to themselves. The masonry will generally be between 1 1/2" to 2 3/4" thick.
Its main function will be decorative. Many cladding designs have units fixed in such a manner that normal masonry coursing and jointing is not part of the design and continuous perpendicular jointing is common.
Cladding can be laid on a bed of mortar or retrospectively jointed.
In many instances it is simpler to retrospectively joint the cladding as the bed width does not offer sufficient stability for the masonry to stand one unit on top of another and depends on fixing by mechanical means.
The design of the fixings will determine whether or not the construction can be built without movement joints. Fixings that have horizontal and vertical movement slots but provide lateral restraint usually allow walls to be constructed without movement joints, provided a mortar with a low modulus of elasticity is used.
The need for compressive strength in this type of work is not significant with a mortar of 150 - 300 at 28 days being usually adequate for the purpose.
NHL 2 and NHL 3.5 are very suitable binders for the production of cladding mortars. Their elasticity moduli is adequate in most instances and their free lime content, mainly responsible for plasticity, is high (25% and 50% respectively).