*All new Roundtower NHL bag designs will be introduced gradually once old stocks of bags have been used*
Natural Hydraulic Limes (NHL) are made from limestone containing impurities which enable a hydraulic set. They are supplied as dry powders, when mixed with sand and the addition of water they set through a chemical reaction known as hydration. This chemical set allows for NHL mortars to be used in damp and more exposed locations and produce an earlier resistance to frost than lime putty.
Natural Hydraulic Lime (NHL)is supplied in three European classifications, NHL 2 (feebly hydraulic), NHL 3.5 (moderately hydraulic) and NHL 5 (eminently hydraulic). These grades are based on compressive strength.
NHL has a number of qualities:
Roundtower NHL 5 offers the maximum strength of the 3 classifications for NHL (Natural Hydraulic Lime) and as such we would advise caution as to exactly where it’s used.
While it can be used for most typical mortar applications especially those in more aggressive environments, and only then onto suitable, durable backgrounds; this is a binder with limitations in conservation. However, it will make an appropriate masonry mortar for marine applications including those within the tidal zone or flow in rivers etc.
Roundtower NHL 5 is used extensively for limecrete flooring.
Roundtower NHL will set in the presence of water which makes it ideal for use on exterior applications.
Roundtower NHL 5 is available in 25kg bags.
Each pallet contains 56 X 25kg bags.