St. Astier Lime Mortars
Natural hydraulic limes are coming back to take their rightful position as
building materials suitable for restoration, conservation and new
construction. Cement displaced these materials as it offered a quicker set
and more strength when these became the construction industry main
parameters for building mortars. However, already at the beginning of the
20th century, problems related to the chemical reactions caused by cement
and damaging effects caused by the excessive strength produced in cement
mortars were noticed. Nevertheless, the speed at which the cement industry
developed and its acquisition of most quarries that produced hydraulic lime
to obtain the raw material for cement production was astonishing. Hydraulic
limes disappeared. In building terms this coincided with the appearance of
damage to old masonry or soft stones, due to the hardness of cement
mortars, deterioration due to sulfate and alkali-silica reactions, loss of
durability and poor compatibility of cement mortars with existing old
mortars, which were all lime based.
The lack of hydraulic limes promoted the use of hybrid mixes of cement/lime/sand whenever restorers and builders tried to diminish the excessive strength of pure cement mortars, but the presence of cement, even in these diluted forms, still produced undesirable chemical reactions.
Pure and natural hydraulic limes (NHL) are coming back because
they offer the right, and authentic, materials. They do not contain
the damaging chemical components of cement, they set quickly,
and are easy to mix even in conventional mixers. They will produce
building mortars of various strength, but allow for movements
as they achieve their strength over a longer period of time and
have a far better elasticity moduli than cementitious mixes. NHL
mortars, although resistant to water penetration have high vapor
exchange properties thus avoiding condensation. These are perennial
materials with centuries of life ahead of them. Once applied with
normal and current working practices and having used a well graded
sharp sand, they will perform in the harshest climatic conditions.
Product Range: Saint Astier produces NHL 5 (eminently hydraulic),
NHL 3.5 (moderately hydraulic) and NHL 2 (feebly hydraulic). This is
a unique range at the disposal of the specifier, providing for
the correct binder for most uses without having to resort to blending.
Restoration, Conservation and New Build
Why Use St. Astier Pure and Natural Hydraulic Limes
St. Astier pure and natural hydraulic limes (NHL) have been in production for over 150 years. The characteristics of the raw materials are unique and consist of an undisturbed layer of calcareous rock infiltrated mainly by silica with only traces of other minerals. Millions of tons have been used successfully on a global scale, in the most diverse climatic conditions. During this time the uninterrupted experience of the manufacturer has generated a wealth of technical information both scientific and practical which is always available to the user.
1. Purity NO ADDITION of any kind is made to the St. Astier Natural
Hydraulic Limes to enhance their performance.
2. No Need For Blending The St. Astier range of Natural Hydraulic
Limes allows for the selection of the most suitable binder for
the work at hand without having to add pozzolans, cement, plasticizers,
water retainers, waterproofers, etc. Blending introduces considerable
risks, added costs and short and long term results that are uncertain
and therefore potentially costly.
3. Compatibility & Suitability The availability of a range of
binders with different performance characteristics ensures the
compatibility of St. Astier NHL mortars with existing mortars
whatever their age.
4. Free Lime Content (available lime) Responsible for workability
and self-healing in NHL mortars.
5. Versatility Of Use Building and plastering mortars, grouts,
injection, lime concrete and paints are all possible with NHL
products.
6. Elasticity An essential factor in building without construction
joints. Important in minimizing shrinkage and cracking. Allows
for minor movements.
7. Permeability Good vapor exchange qualities allow for condensation
dispersion. No rot. Great benefits to the living environment.
8. Resistance To Salts The absence of any potentially damaging
component or additions (i.e. gypsum or cement) make sulfate attack
and alkali-silica reactions impossible. Existing salts in the
building fabric will pass through and eventually wash off. Excellent
performance in marine environment.
9. Suitable Compressive Strength Unlike cement or cementitious
mixes (1:1:6 etc.) the compressive strength will be achieved gradually,
allowing for movement. The availability of a range will permit
the making of mortars with the required strength without having
to add or blend.
10. Resistance To Weather Early setting means less time for protection
from adverse weather.
11. Self Healing The available lime provides this benefit.
12. Resistance To Bacteria & Vegetation Growth The permanent alkalinity
of the binder inhibits their development.
13. Insulation The excellent vapor permeability of NHL mortars
reduces moisture in walls, therefore significantly improving insulation
levels.
14. Sand Color Reproduction The whiteness of the NHL binders will
reproduce the color of the aggregate used.
15. Reworking All St. Astier mortars can be reworked (8-24 hours),
reducing waste and increasing work rate. This is due to the absence
of cement, gypsum, pozzolans or high aluminates.
16. Recycling Materials built with NHL mortars can be reused.
17. CO2 Absorption Probably the most eco-friendly feature of using
limes. CO2 is re-absorbed during the carbonation of the free lime.
For more information about St. Astier lime mortar, including composition,
qualities, performance, good working practices, mortar analysis
and recommendations, please contact us directly at:
e-mail: transmin@sonic.net
(707) 769-0661 office
(707) 769-0352 fax
-Information compiled from Setra
Marketing sources.
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MSDS NHL
