WO2009019479A1

WO2009019479A1 - Insulating lime mortar composition

Info

Publication number: WO2009019479A1
Application number: PCT/GB2008/002682
Authority: WO
Inventors: Henry Charles Cursham
Original assignee: Henry Charles Cursham
Priority date: 2007-08-07
Filing date: 2008-08-07
Publication date: 2009-02-12
Also published as: GB2464657A; GB201003820D0; GB0715414D0

Abstract

The present application describes methods of coating a surface with an insulating lime mortar composition which comprises a lime component, an aggregate component, and an insulating component, by supplying the composition to a spray gun by pumping and spraying it onto the surface. The application also describes lime mortar compositions themselves comprising a non-hydraulic lime putty; an aggregate component; and an insulating component having at least one of perlite, Light Expanded Clay Aggregate (LECA), polystyrene, and cork. Methods of forming the compositions, and uses of the compositions to form a thermally insulating layer on various surfaces or in void spaces are also described.

Description

INSULATING LIME MORTAR COMPOSITION

TECHNICAL FIELD

This invention relates to lime mortar compositions and their use. In particular lime mortar compositions comprising an insulating material, to improve the thermal insulating properties of the mortar. The lime mortar compositions are pumpable so that they can be easily applied to surfaces using known mortar pumping and spraying techniques .

BACKGROUND

Lime mortar is a traditional building material that has been used for many years to coat interior and exterior walls of buildings to provide an attractive and technically advanced finish. In recent times, lime mortars have been largely replaced by cement mortars that can be applied to a wall and then, in the case of internal walls, finished with a fine layer of gypsum plaster to achieve a smooth finish. Cement mortars typically "go off" or harden much more quickly than lime mortars so saving time when multiple mortar layers are required. However, lime mortar is a softer more breathable material than cement mortar or gypsum plasters. This has the advantages, particularly in older buildings, that the mortar accommodates small movements in the structure without cracking and also allows moisture to escape from both the substrate to which the mortar is applied and also from the interior of the building so reducing damp problems often associated with older constructions and internal condensation in newer designs where doors and windows are often sealed against draft and fire. To improve the strength of traditional lime mortar it is known to incorporate fibres such as animal hair or plant fibres into the mortar mixture. However, this addition of hair or fibre to the mortar is not sufficient (e.g. not in sufficient quantity) to achieve a significant increase in the insulating effect of the mortar.

Both traditional lime mortar and modern cement mortar have relatively poor thermal insulation properties. In a modern building one or more layers of insulation material are typically incorporated into the wall, e.g/ as a cavity wall filling or thermal insulation boards, to provide thermal insulation before the mortar is applied. However in older buildings, this may not always be possible due to the construction of the building or restrictions on materials used for renovation. Furthermore use of insulating boards does not retain the shape of the original wall. In some applications, particularly renovation of old buildings, it may be important to retain the shape of the original wall so it is not straightforward to use insulating boards . In addition where insulating fibrous materials are used, glues negate the breathability of the walls and many other board materials such as gypsum board, have silver foil backing which prevents the vapour transfer which is one of the major benefits of lime mortar.

When insulating boards are used, the finish of the wall also tends to be much less substantial than a lime mortar finish. For example, the wall can sound hollow when plaster boards are used and specialist fixings are required to attach objects (e.g. shelves, pictures etc.) to the wall, whereas with a lime mortar finish, a solid wall is obtained and the ability to, for example, drive a nail into the wall is retained. Lime mortar also typically provides a more aesthetically pleasing finish to the surface.

Insulating wall-coating compositions are known and typically these comprise a lightweight insulation material and a binder.

Lime has been used as the binder, however these compositions are not pumpable because the pressure used in the pumping process tends to cause the insulation^' material to be crushed so losing much of its insulating properties.

Additionally, known lime mortar compositions incorporating animal hair or plant fibres and other insulating materials, are pumpable under some conditions but the insulating properties of these are relatively poor due to the inability to apply any meaningful coating thickness to a surface because the material cracks and dislocates if applied too thickly.

When applying a mortar composition to an upright surface such as a wall, only a certain amount of the mortar can be applied before it "slumps" i.e. either starts to slide down the surface under gravity giving a thicker coating at the bottom than the top, or it falls off the surface altogether as the weight of the wet mortar applied becomes too great. Traditionally, lime mortar cannot be applied in single coats greater than about 10mm thick. For thicker coatings, individual layers of mortar must be applied and then left to dry (or "go off") before further layers are applied and allowed to dry to build up the desired thickness of material. This is both time consuming and labour intensive.

_ 2 - The present invention provides a pumpable lime mortar composition comprising an insulating material. Additionally, this composition can be applied to a surface in thicker coatings than a normal lime mortar.

OUR PROPOSALS

In one aspect, the present proposals include a pumpable lime mortar composition having enhanced thermal insulation properties.

Methods of formation of the lime mortar composition, methods of application to various surfaces, and uses of it are also aspects of our proposals .

Compositions

The pumpable lime mortar composition comprises at least a lime component, an aggregate component and an insulating component.

The lime component may be hydraulic or non-hydraulic lime but is preferably non-hydraulic lime putty. More preferably the lime component is mature non-hydraulic lime putty, i.e. non- hydraulic lime putty that has been stored in the absence of carbon dioxide for a period of time (typically between at least 6 months and 48 months) to allow it to mature. Longer maturation is preferable. In the proposed compositions, the non-hydraulic lime component is preferably matured for about 4 years before use.

Non-hydraulic lime is preferred because mortars made with this type of lime set via a different mechanism to those made with hydraulic lime. Non-hydraulic lime mortars set by reaction with carbon dioxide, e.g. atmospheric carbon dioxide, to produce calcium carbonate and set the mortar. By contrast, hydraulic lime mortars set by reaction with the water in the mix. This has two disadvantages: first, once a hydraulic lime mortar has been mixed, it cannot be stored for very long because it will go off (i.e. set hard); second, hydraulic lime mortars have a greater environmental impact than their non- hydraulic counterparts because the process used to make the lime releases CO₂ which is not reabsorbed from the atmosphere by the setting reaction as it is for non-hydraulic lime mortars .

Suitable non-hydraulic lime is available from the Buxton Lime Company and from Singleton Birch Ltd. , UK.

The aggregate component is preferably a graded stone powder having a range of particle sizes, for example a stone powder having particle sizes ranging from about 3mm down to dust (e.g. less than about 0.1mm) is particularly useful. If the aggregate contains too small a quantity of small particles (e.g. dust), the resultant mortar cannot easily be pumped using standard pumping and spraying apparatus because it forms a solid mass when compressed rather than flowing as is required for a pumpable mortar. If the aggregate contains too large a quantity of small particles (e.g. dust), the resultant mortar has a tendency to crack as it dries. Preferably the aggregate component is a fine aggregate component selected from one or more of graded stone powder (e.g. Oolitic stone dust), calcium carbonate (optionally recycled calcium carbonate) and ash materials. Preferably, the aggregate is not building sand or sharp sand and is preferably not washed because these typically do not contain the required grading of particle sizes necessary to produce a mortar which is pumpable and does not crack as it dries. Furthermore, sands also have a high silica content which increases overall density of the resultant mortar, which in turn undesirably reduces thermal resistance (i.e. resulting in a less insulating mortar) . Siliceous materials are also not porous which reduces the absorption and breathability of the mortar product. It is also suspected that silica materials may have a detrimental effect on the longevity of lime mortars, especially where higher rates of water absorption and release are encountered. Preferably the aggregate component is a non- siliceous material.

The aggregate component may, for environmental reasons, be a recycled aggregate.

The lime mortar composition comprises between about 1 part and about 10 parts by volume aggregate component per 3 parts by volume lime component, preferably between about 2 parts and about 5 parts by volume, more preferably about 3 parts by volume per 3 parts by volume lime component .

The proposed compositions may be mixed by preparing a "base mix" comprising between about 1 part and about 8 parts by volume, preferably between about 2 parts and about 5 parts by volume, more preferably about 3 parts by volume aggregate component and about 1 part by volume lime component. This base mix may then be combined with further ingredients to achieve a desired mortar composition. The insulating component is a low density material, typically a low density rock or synthetic component. Preferably the insulating component is selected from one or more of perlite (preferably expanded perlite) , Light Expanded Clay Aggregate (LECA), polystyrene (preferably expanded polystyrene) balls. Preferably the insulating component is a mixture of perlite (preferably expanded perlite) and LECA.

Suitable expanded perlite and LECA products are available from the Silvaperl Company.

Alternatively, the low density insulating material may be natural cork.

-Natural cork has good insulating properties and a low density and has the added advantage of being resistant to rotting. Where cork forms the insulating component in a composition as described herein, it can have a lifetime of many tens, of years . The embodied energy contained in natural cork is minimal as there is no manufacture process involved in its production. The only process required for the production of a material, suitable for use in a composition of the present invention is that of crumbling and grading. Furthermore, the material is naturally grown and therefore absorbs carbon from the atmosphere during growth and can easily be harvested from sustainable sources. Natural cork is also very low density and so requires little fuel for the transport of the raw material, compared to other denser raw materials .

We believe that compositions of the present invention utilising natural cork as the insulating component have a very low, and possibly even negative, carbon footprint, i.e. very low carbon emissions or even removal of carbon from the atmosphere as a direct result of its use.

The insulating component preferably has a bulk density of less than about 1 g/cm³, preferably less than about 0.8 g/cm³, more preferably less than about 0.3 g/cm³. In preferred embodiments, the density of the insulating component is between about 0.02 and about 0.3 g/cm³. Generally, the insulating component is preferred to have as low a density as possible. However it must also provide sufficient strength to allow the resultant mortar to be pumped without significantly crushing the insulating component.

Preferably the insulating component has a range of particle sizes, preferably between dust (less than about lOOμm) and about 12mm, more preferably between dust and about 8mm.

Preferably, the insulating component is a mixture of perlite (e.g. expanded perlite) and LECA, more preferably, perlite having a particle size range of about 0.6mm to about 5mm and LECA having a particle size of about 1 to about 8mm.

Where the insulating component is natural cork, it is preferably cork granules having a granule size range of about 0.1mm to about 10mm.

The amount of insulating component present in the lime mortar composition is between about 2 and 12 parts by volume, more preferably between about 4 and 8 parts by volume, more preferably about 6 parts by volume, per 3 parts by volume lime component .

If a "base mix" is prepared (as described above) , about 2 to 12 parts by volume, more preferably between about 4 to 8 parts by volume, more preferably about 6 parts by volume insulating component is incorporated per 1 part by volume "base mix" .

Preferably, the insulating component comprises about 4 parts LECA and about 2 parts perlite (preferably expanded perlite) . More preferably, the insulating component comprises 2 parts perlite having a particle size range 0.6mm-5mm, 2 parts LECA having a particle size range l-4mm and 2 parts LECA having a particle size range l-8mm.

Where a "base mix" is prepared and additional components are added, it may be necessary to add additional lime component to maintain a desired ratio of lime component to aggregate + insulating component.

In the proposed mortar compositions, it may be preferable to have a ratio of lime component to aggregate + insulating component of between about 1 to 2 and about 1 to 4, preferably about 1 to 3.

Additional water may be added to the mortar mixture to achieve the required consistency for optimum pumping. Typically, a uniform consistency and mixture is required and water may be added until the mortar flows under pressure so allowing it to be pumped (i.e. the composition is "flowable") . The amount of water depends on a variety of different factors, such as the dryness of the aggregate component, the temperature of the mortar and the atmospheric humidity. For example, in warm conditions, typically less water is necessary than in cooler conditions due to the changes in viscosity of the composition. For mortars containing non-hydraulic lime, the lime component already contains some water. However, for hydraulic lime mortars, additional water will be necessary.

In the proposed non-hydraulic lime mortar compositions, between about 4 litres and about 50 litres, preferably between about 8 litres and about 30 litres of water may be added to a 1 m³ batch of mortar composition.

For hydraulic lime mortar compositions, sufficient water is added to fully hydrate the lime component and further water may be added as required and as described above for non-hydraulic lime compositions.

If too much water is added, the mortar becomes too wet and slumps and may crack when applied to an upright surface. If the mortar does not contain enough water, it does not flow and becomes difficult or impossible to pump.

The proposed compositions have the additional benefits that they are sustainable, recyclable and have low environmental impact and a low carbon footprint.

The proposed lime mortar compositions are pumpable. This means that they can be applied to a surface (e.g. an upright surface) using known pumping and spraying techniques. For example, the composition is driven through a pipe (e.g. by piston or rotor, stator, auger etc.) and through a nozzle to which compressed gas (typically compressed air) is supplied. At the nozzle, the compressed gas supply causes the lime mortar to spray out from the nozzle allowing a user to direct the spray of mortar against an application surface. Furthermore, in the context of insulating lime mortars, "pumpable" means that the insulating material remains largely intact during the pumping process, i.e. it is not crushed by the pumping pressure so degrading its insulating properties.

Lime mortars presently used in the industry are usually a mixture of lime and sharp sand and are typically not pumpable without the use of additives, rendering them non-pure and not in keeping with traditional lime compositions.

Cement mortars and known lime mortars can be applied using pumping technology but in order to make the composition flow, it is necessary to add a flowing additive, such as an oil or plasticiser. Of course, the addition of such flowing additives to traditional lime mortar is undesirable in situations where traditional building methods and materials are being used, e.g. restoration of old lime plaster walls, because it does not faithfully replicate the composition or properties of the original building materials. Also, it is suspected that these flowing additives may have a detrimental effect on the ageing of the lime mortar with an associated reduction in performance.

The ability to pump the proposed lime mortars offers numerous advantages that cannot be achieved using either known lime mortar compositions (which in any case are not pumpable) or cement mortars . First, when the proposed lime mortars are pump-sprayed onto an upright surface (e.g. a wall), they can be applied in much thicker single layers than either known lime mortar or cement mortar. This is thought to be due, at least in part, to the inclusion of the insulating component in the proposed mortar compositions which reduces the density of the mortar allowing a greater volume to be applied to the surface before it becomes too unstable under its own weight and slumps or detaches from the surface. The proposed lime mortar compositions can be applied in a single coat of up to about 85mm thick, and in some cases even thicker, e.g. up to about 100mm thick. Typically the proposed lime mortar compositions can be applied in a single coat having a maximum thickness between about 50 and 85mm. This is significantly thicker than known lime mortars which can only be applied in a single coat having a thickness up to about 10mm. If a known lime mortar containing sand is applied to a surface in a coat thicker than about 10mm, the coating tends to crack as it dries and detach from the surface.

Second, the ability to pump the proposed lime mortars means that a surface can be coated much more quickly and with far greater adhesion than is possible using known lime mortars which are applied by hand (normally by trowelling the mortar against the surface to achieve a bond) . When the proposed mortar is applied by pumping and spraying, it impinges on the surface with a greater force than is achievable by merely pressing the mortar against the surface with a trowel tool. In fact, the application by pumping is akin to traditional lime mortar application methods (which have now largely fallen out of use) in which the mortar is thrown against the surface to achieve a strong bond. Of course pumping offers the additional advantage of higher application speeds and lower labour requirements .

Third, the application of the proposed lime mortars using pump- spray apparatus in which compressed air is used to spray the mortar from the nozzle means that the lime mortar is aerated as it is ejected from the nozzle. As mentioned above preferred embodiments use non-hydraulic lime which sets by reaction with carbon dioxide. Therefore7 the aeration of the proposed lime mortar as it is ejected from the nozzle means that carbon dioxide is distributed throughout the mortar resulting in an improved set of the mortar on the surface.

The proposed insulating lime mortar compositions provide advantages over known lime mortars in that they offer greatly enhanced thermal properties. The insulating properties of known lime mortars are relatively poor whereas the proposed lime mortars have relatively enhanced insulating properties. Typically the proposed lime mortars have a thermal conductance value U, in the range of about 0.5 to about 1 W/(K.m²) at 100mm coating thickness, preferably about 0.8 W/(K.m²) at about 100mm thick. These thermal properties are provided in addition to the desirable breathability and flexibility of known lime mortars discussed above.

The proposed insulating lime mortar compositions preferably have a density of about 1 to 2 g/cm³, more preferably about 1.1 to 1.5 g/cm³, even more preferably about 1.3 g/cm³ when wet. When dry, the proposed insulating lime mortar compositions preferably have a density of about 0.5 to 1.5 g/cm³, more preferably about 0.75 to 1 g/cm³, even more preferably about 0.9 g/cm³.

When the proposed insulating lime mortar compositions have been applied to a surface by spraying and allowed to dry, the density may be lower than when the wet mortar has simply been allowed to dry without undergoing the spraying process. Where the proposed compositions have been applied by spraying and allowed to dry, the density is preferably between about 0.5 and 1 g/cm³, more preferably about 0.8 g/cm³ or even less.

As explained above, the proposed lime mortars also benefit from all of the advantages of being pumpable.

The proposed lime mortar compositions may also contain one or more of the following components.

1. Fibrous material. This may be added to the lime mortar compositions to enhance the strength and cohesion of a mortar coat. Examples of useful fibres include natural fibres (such as plant fibres, e.g. hemp fibres, or animal hair) and synthetic fibres. The nature of the synthetic fibres is not critical but they are preferably easily mixed into the proposed mortar compositions (some natural hairs are not easily mixed in) . An example of a suitable fibrous material is fibrous polypropylenes such as those sold by the ADFIL (RTM) company. Typically about 0.005 to about 0.1 vol. %, preferably about 0.01 to about 0.05 vol. %, fibrous material may be included in the mortar composition.

2. Hydraulic lime. When the lime component is not hydraulic lime, addition of this can decrease the setting time of the lime mortar. However, it may have the effect of producing a mortar which, when set, is denser and harder than mortars which do not contain hydraulic lime. This typically results in impaired insulation properties and a reduction of carbon dioxide absorption as the mortar sets .

3. Pozzolan. These are typically siliceous materials which react with calcium hydroxide (lime putty or "slaked lime") to set into a cementitious material. Examples include burnt clay materials, silica fume, volcanic ash, fly ash, high reactivity metakaolin, and ground blast furnace slag. The addition of pozzolan (s) can impart faster setting properties to the lime mortar. However, the set is by reaction of the pozzolan with the lime component (in a similar manner to hydraulic lime mortars or cement mortars) so the storage lifetime of the mortar is compromised and the mortar absorbs less carbon dioxide from the atmosphere on setting than does a mortar without pozzolans .

4. Colouring materials, e.g. known dyestuffs. These can be used to provide a mortar having a uniform colour throughout, e.g. for decorative purposes. 5. Surface coatings applied onto the mortar to finish and decorate the mortar surface.

The low environmental impact of lime mortars is well known. They are close to carbon neutral materials (particularly non- hydraulic lime mortars) when they have set because the carbon dioxide released when the lime is formed is offset by carbon dioxide absorption when the non-hydraulic lime mortars set . [N. B. This benefit is not achieved by hydraulic lime mortars or cement mortars which do not set by carbon dioxide absorption.]

Furthermore, this low environmental impact is accompanied in the present proposals by the enhanced thermal properties compared to both known lime mortars and cement mortars, and the ability to pump the material which provides the advantages discussed above.

Compositions as described herein allow very high performance of moisture ingress and evaporation ensuring a dry environment of the materials. Moisture is the vital ingredient for all growth of mould and germs so exclusion of this inhibits mould/germ growth .

The present compositions are also strongly alkaline which further inhibits mould growth and hence inhibits or prevents rotting of a building if continually exposed to water through lack of maintenance.

The present compositions can be used as solid mass without failure or cracking. They carry the performance properties of traditional lime mortars with the benefits of insulation values and can be used to depths impossible with normal lime putty- mortars .

Production of compositions The proposed lime mortar compositions are made by simply- blending together the desired components. Therefore the mortars can be provided to the site where they are to be used either ready mixed for use, as a powder (if the composition is based on hydraulic lime) to which water can be added on site before use, or as a kit of different components, which may include some mixed components, that can be mixed together on site before use.

uses A further aspect of these proposals is the use of the proposed insulating, pumpable lime mortars to provide an insulating surface covering (e.g. a wall covering). The proposed lime mortar composition can be applied onto a surface such as a wall, (preferably an internal wall) , preferably by spraying, in a single coat to a thickness of up to about 100mm, preferably up to about 85mm. This offers considerable benefits (as discussed above) over known lime mortars and cement mortars which can only be applied in relatively thin single coats, e.g. up to 10mm, which must each be allowed to dry before the next coat is applied.

Therefore, applications of the compositions and methods described herein include, amongst others, preparation of an insulating external lime render, preparation of an insulating internal lime plaster, void filling insulation material, stud wall infill, timber frame building infill panel and attic/roof space insulation.

Pumping Normal mortar pumps can be employed to 'spray' the compositions onto the wall substrates. Pumps can be 'rotor and stator', compressed air 'blown' or 'piston' .

The compositions behave best with a piston machine as the pumping action does not- alter, crush or 'grind' the mortar into finer pastes, so this is preferred.

The pump can be driven by petrol/diesel engine or electricity. Electric pumps can be 3 phase, 24Ov or 11Ov. The 24Ov pump is preferred as the pump is powerful and controllable. 11Ov may not be powerful enough to raise the material to the required heights and 3 phase electricity is not normally available on most projects. Fuel engines are less desirable due to the fumes and noise. They are also more difficult to control.

Combined with the piston operation, compressed air is fed separately to the spray nozzle. This 'atomises' the pumped material, ejecting it with great force onto the substrates.

Pressure utilised is typically in the range of about 0 - 25 bar (0 - 350 psi) depending on the height of lift from the pump.

Compressed air is preferably fed at a rate of about 10 - 120 cubic feet per minute dependant on the speed of pumping required. The pipes, carrying the composition, are typically made from reinforced rubber. The pipes can be ^λnon-expanding' although flexible or partially elastic and flexible. Elastic pipes are preferred as they marginally expand and contract ensuring a better and more consistent flow of material to the spray gun. This is particularly important when using a piston pump due to its pulsing nature.

The pipes can be laid in lengths up to the power/ability of the pump. Typically pipe length does not exceed about 50m, with a vertical lift of about 20m. However the horizontal distance is greatly reduced as a direct consequence of height/lift.

Spraying First, as with all pumping, the pipes are typically primed with a wet and ^v fat ' composition, in order to stop the pipes blocking due to the composition becoming dry at the front when passing through the clean dry pipe.

Once the mortar has been pumped up and is flowing freely from the gun, the gun can then be used to spray the composition by the addition of compressed air to the gun.

The gun is preferably held approximately 75 - 300 mm from the substrate and the composition is laid onto the wall in horizontal passes starting at the bottom of the substrate. It is preferably applied to the wall in initial depths of approx 30 mm in the first pass, immediately returning for subsequent passes to build up to an approximate combined depth of 60 - 70 mm, as a first coat. Overall a first coat is preferably between about 20mm and about 70mm thick. This first coat can then be 'deftly' flattened in as few passes as possible with a broad flat tool, leaving a broken and open surface . Minimal work to the wet material is preferred as there are dangers involved in the process, namely:

Causing a smoothed skin to the coating resulting in differential densities within the composition and consequent cracking;

There is a tendency to pull the coating off the substrate due to over working. This will cause 'slumping' and dislocation of adhesion. -•.

The coat is then allowed to stiffen and partially carbonate.

The consistency of 'stiff crumbly cheese' is typically achieved before any further work is attempted. The composition should however preferably not be allowed to dry fully at the surface.

If this unavoidable due to site pressures, then scratching of a key is required prior to the next coat being applied. This is not however, preferred.

Once the first coat is ready, the second can be applied in exactly the same method as described above.

The depth of the second coat is usually less than the first and typically in the region of about 30 - 40mm. The intention is to achieve an even depth of about 100 mm.

It is advisable to utilise depth markers from the outset in order to ensure consistency of depth of coating. The composition is being used in order to create insulation and this is achieved by its depth/accurate mass. The second application can then be flattened in exactly the same manner as the first coat and for the same reasons.

The material is then preferably left before any further work is carried out until it achieves the same consistency as for the first coat.

Finishing coats Once the material has- achieved the same 'stiff crumbly cheese' consistency, the material-, can be coated and completed typically with one coat of breathable lime plaster skim for internal work or lime render for external work.

Externally, it is preferred to apply two coats of lime render in order to protect the material from the weather and finish the render in any normal manner of finish.

It is also preferred to employ a traditional lime wash in order to further protect the material. However a modern breathable paint such as ^λKeim' could also be employed.

Another aspect of the present proposals is a composition or use as described in the examples.

In respect of numerical ranges disclosed in the present description and claims it will of course be understood that in the normal way the technical criterion for the upper limit is different from the technical criterion for the lower limit, i.e. the upper and lower limits are intrinsically distinct proposals .

EXAMPLES

The following examples illustrate the present proposals but do not limit them in any way.

Composition Example 1 A base mortar is formed by mixing 3 parts by volume graded Oolitic Cotswold stone dust (3mm to dust) with 1 part mature lime putty (matured for 4 years) (supplied by Buxton Lime company) .

This ba_.se mortar then forms the basis and acts as a binder to which various insulating materials can be added.

Into 3 parts base mortar (described above) is mixed 2 parts by volume perlite (3-6mm) (Silvaperl Ltd.), 2 parts by volume LECA (l-4mm) (Silvaperl Ltd.), 2 parts by volume LECA (l-8mm)

(Silvaperl Ltd. ) , 2 parts mature lime putty (matured for 4 years) (Buxton Lime company), and 0.02% by volume of the total composition polypropylene fibres (supplied by Fibrin industries) . Water was added to form a flowable composition.

This mortar composition is easily pumpable and can be applied to an upright surface by spraying to form a stable coating having a thickness of up to 85mm in a single coat.

This composition has a wet density of 1.3 g/cm³ and a dry density of 0.92 g/cm³. This composition has a U value of 0.806 W/(K.m²) for a dry- coating having a thickness of 100mm.

Composition Example 2

A composition was prepared using the methods described in composition example 1 but using the following ingredients:

3 parts by volume crushed oolitic limestone dust (graded 3mm to fine dust) ; ^"---.

1 part by volume perlite Silvalite P45 (3-6 mm) (Silvaperl Ltd.) ;

1 part by volume LECA (1-4 mm) (Silvaperl Ltd.);

1 part by volume LECA (2-10 mm) (Silvaperl Ltd.); 2 VT. parts by volume mature lime putty (matured for 4 years) (Buxton Lime company) ;

0.02% by volume polypropylene fibres ("Fibrin" from Adfil Anglo-Danish Industrial Fibres); and

Water to form a flowable composition.

Composition Example 3

3 parts by volume crushed oolitic limestone dust (graded 3 mm to fine dust) ;

3 parts by weight 'Crumbled' cork granules (0.1-10 mm);

2 Vi parts by weight mature lime putty (matured for 4 years) (Buxton Lime company); and

Water to form a flowable composition. Use Example 1

The composition described in the "composition example" above was successfully sprayed directly onto stonewalls, concrete blocks and various other substrates to depths of up to 85mm in single coats.

After spraying onto a stonewall and being allowed to dry, the density of the mortar was 0.78 g/cm³.

Use Example 2 - Internal Stud Wall

On occasion it is-.necessary and/or desirous to fill timber stud wall construction.

Traditional wooden lath was applied to the outside faces of the studs, leaving two lath gaps every 500mm. Through the gaps, starting at the bottom of the wall, the composition prepared in composition example 2 was pumped into the void up to the level of the 1^st horizontal gap. Laths were then fixed across the gap and more material then pumped in from the next gap up.

On the first day it was not possible to achieve a height greater than 1.8m due to the pressure of slump exerted onto the laths and consequent distortion. Vertical battens were tied opposite each other, to each other, between the studs in order to stiffen the laths and reduce distortion.

The work was then completed the second day, to a height of 3.6m with the same methods. The surfaces of the laths were then scraped off, when wet and the whole allowed to dry/carbonate to a 'stiff crumbly cheese' consistency.

Once stiff, the battens were removed and the wall was then plastered with lime materials in the normal manner. The result was a very solid and fine finish to an internal wall .

Use Example 3 - Attic/Loft Insulation

In a very traditionally constructed 16^th century roof to a Yeoman Farmers house insulation was required and an internal finish of lime plaster. At that stage there was no wish to remove the tile and felt coverings to the external face. The felt was causing problems of condensation and consequent damp penetration to the timber structure.

Lime mortar compositions, of the type described in this application have properties of moisture absorption and release. This results in the removal of condensation forming on the internal face of the felt, where it forms a 'cold bridge'.

Traditionally, the tiles were plastered with lime mortar between the rafters to a depth of approx 25mm. This material acts as a breathable membrane and wicking device to remove condensation and at the same time reduce drafts whilst further securing the tiles in position.

The felt was cut away from the underside of the tiles. Using the same method of timber lath applied to the timber structure of a stud wall (as in Use Example 2), lath was applied to the internal face of the rafters to a height of approx 500mm with a gap left of two lath width and continued to the apex of the roof on each side in the same manner. Starting at the bottom, the void was filled with composition according to Composition example 2, by the use of the pump up to the gap left for the purpose of filling the void.

Laths were applied to the gap, once filled and the process repeated again until the apex was reached.

In this instance, to -avoid adding additional point load imbalance of the structure, the work was carried out evenly throughout the roof space .

The material is, in one application, used to fill the void between the roof tiles and the lath.

The surface of the lath was scraped off and the material allowed to dry/carbonate to the same consistency as above of 'stiff crumbly cheese' before the final internal lime skim coat was applied.

Achieved is an insulated, moisture efficient, lime plastered and traditional attic roof space.

Use Example 4 - Timber Frame Building Infill Panels Modern materials do not have good success when attempting to infill traditionally constructed timber frame buildings. One problem to overcome is movement in the frame resulting in an opening up of the join between timber and infill, causing moisture ingress. This ingress may be exacerbated by the capillary action of impervious materials creating a non- permeable gap that simply encourages ingress of moisture.

Modern materials have significant problems with interstitial condensation, between the layers of thin infill materials and their less than porous nature.

The present compositions can be used to create a solid panel within the frame opening negating the above problems. Any moisture ingress is simply soaked/wicked away into the body of the composition and thence dried out through the surface of the panel. The exterior can be simply maintained by application of lime wash over the forthcoming years .

A building was measured accurately to record the size and shape of each panel to fit the building frame.

Off site panels were made to fit the frame from a timber batten structure to give rigidity to the panel. The panels were then 'cast', using the composition from Composition Example 2, into panels of the correct size and shape to fit all the openings of the frame .

Prior to casting stainless steel screws were inserted ready to fix the panels in place, into the timber frame of the building.

Once the panels were ready, carbonated and almost dry, the panels were transported to site and fixed in place by bedding with a lime putty mortar and then utilising the screws to permanently fix them in place. The external faces and internal faces were then finished off with lime render and plaster then lime washed to finish.

Several panels were ^xcast' in-situ due to local site logistical problems. The base composition was cast in one solid mass and flattened off leaving the surface open and rough, ready to receive the finishing coats of plaster and render once of a 'stiff crumbly cheese' consistency.

The advantages are as above; high performance wicking of ingressed moisture; --high performance evaporation of ingressed moisture; high performance insulation values; no interstitial condensation; no internal condensation; traditional finish of lime wash and therefore appearance; competitive financial values; long life in use service.

Claims

CLAIMS :

1. An insulating lime mortar composition comprising: a lime component; an aggregate component; and an insulating component characterised in that the lime component is a non-hydraulic lime putty and the insulating component comprises at least one of perlite, Light Expanded Clay Aggregate (LECA) , polystyrene, and cork.

2. An insulating lime mortar composition comprising 3 parts by volume lime component;

1-10 parts by volume aggregate component; and 2-12 parts by volume insulating component.

3. A composition according to claim 1 or 2 , wherein the aggregate component is non-siliceous material.

4. A composition according to claim 3, wherein the aggregate component is a graded stone powder having particles sizes ranging from about 3mm down to dust.

5. A composition according to any one of the preceding claims, wherein the insulating component has a bulk density of less than lg/cm³.

6. A composition according to any one of the preceding claims, wherein the insulating component has a range of particle sizes between about 12mm and dust.

7. A composition according to any one of the preceding claims, wherein the insulating component is a mixture of perlite having a particle size range of about 0.6mm to 5mm and LECA having a particle size range of about lmm to about 8mm.

8. A composition according to any one of claims 1 to 6, wherein the insulating component is natural cork having a particle size range of about 0.1mm to about 10mm.

9. A composition according to any one of the preceding claims having a thermal conductance value (U) in the range of about 0.5 to about 1 W/(K.m²) for a 100mm thick coating when dried.

10. A composition according to claim 1 comprising:

3 parts by volume crushed oolitic limestone dust graded 3mm to fine dust;

1 part by volume perlite (3-6 mm) ; 1 part by volume LECA (1-4 mm) ;

1 part by volume LECA (2-10 mm) ;

2 ¹A parts by volume mature non-hydraulic lime putty; 0.02% by volume polypropylene fibres; and water to form a flowable composition.

11. A method of coating a surface with an insulating lime mortar composition, the insulating lime mortar composition comprising a lime component, and aggregate component and an insulating component, characterised in that the method comprises supplying the composition to a spray gun by pumping and spraying the composition onto the surface to form a coating.

12. A method according to claim 11, wherein the composition is as defined in any one of claims 1 to 10.

13. A method according to claim 11 or 12 , wherein the coating is applied in a single application to a thickness of about 20mm to about 70mm.

14. Use of a composition according to any one of claims 1 to 10 or a method according to any one of claims 11 to 13 to form an internal insulating lime plaster, an external insulating lime render, a void filling insulating material, stud wall infill, infill panel for timber frame building or attic/roof space insulation.