GB2277926A

GB2277926A - Fire mortar

Info

Publication number: GB2277926A
Application number: GB9312768A
Authority: GB
Inventors: Derek Alfred Ward
Original assignee: Environmental Seals Ltd
Current assignee: Environmental Seals Ltd
Priority date: 1993-05-14
Filing date: 1993-06-21
Publication date: 1994-11-16
Anticipated expiration: 2013-06-21
Also published as: GB9312768D0; GB2277926B; GB9309941D0

Abstract

A fire resistant mortar comprises a calcium aluminate cement and an inorganic fibre material which may be a ceramic fibre or a man-made mineral fibre such as rockwool fibre or glass fibre. Lightweight load-bearing slabs are formed from the fire mortars e.g. floor or ceiling slabs. The fire mortars may be incorporated into ceiling or wall panels and may take the place of conventional plasterboard. The panels may incorporate covering layers 1 and 2 of card of paper, fire mortar 3 and intumescent layer 4 of exfoliating graphite or alkali metal silicate. <IMAGE>

Description

FIRE MORTAR The present invention relates to a fire resistant mortar for use, inter alia, in the construction of flooring materials for buildings, to methods in the preparation thereof, and to wall and ceiling panels comprising the fire mortar.

Fire resistant mortars are known, but a problem with existing fire mortars is that they tend to be somewhat heavy, which thereby complicates the construction of for example floors or ceilings, as a result of the additional support shuttering needed to support the mortar whilst it is setting. A further problem with existing fire mortars is that they tend not to be capable of being drilled easily using conventional tools, and this makes it more difficult to fasten surfaces made from such fire mortars to other building components.

It is an object of the present invention to provide a fire mortar which is lighter than many fire mortars currently in existence, and which can easily be drilled to receive fittings such as screws and like fastening means, whilst remaining resistant to the heat generated in fire situations.

A further object of the present invention is to provide a panel having improved fire resistant properties which can be used in place of conventional plasterboard.

In a first aspect, the invention provides a fire resistant mortar comprising a calcium aluminate cement and an inorganic fibre material.

The inorganic fibre material preferably is a ceramic fibre (eg. an alumina silicate fibre) or a Man-Made Mineral Fibre (MMMF) such as rockwool fibre or glass fibre.

It is preferred that the mortar contains up to about 85% by weight inorganic fibre material. The inorganic binder may be formulated together with a binder, for example a polymeric binder such as a polyacrylate or a polyvinylacetate. In one embodiment the mortar contains up to about 85 by weight of a mixture of the inorganic fibre and a binder. More preferably, the mortar contains between 60 and 80% by weight of the inorganic (eg.

ceramic), fibre. The mixture of inorganic fibre and binder can contain up to about 15% by weight of binder, and more particularly contains up to about 10% by weight of binder.

The typical composition of a calcium aluminate cement, as determined by chemical analysis, can be 38-40% A1203, 3739% CaO, 3-5% SiO2 and 15-18% Fe2O3/FeO. The cement can contain a mixture of monocalcium aluminates, dicalcium silicate and calcium alumino ferrites.

An example of a calcium aluminate cement suitable for use in the mortars of the present invention is "Ciment Fondu Lafarge" manufactured by the Lafarge Aluminous Cement Company Limited of Grays, Essex, United Kingdom.

The fire mortars of the present invention can readily be cast to form lightweight load-bearing slabs, for example, flooring slabs or ceilings. Whereas, normally, during the preparation of a cement floor or ceiling, it is necessary to support the drying cement on a shuttering structure, in the present case, it is sufficient to provide a lightweight support formed of Rockwool fibre slabs.

In a further aspect, the invention provides a method of constructing a floor or ceiling slab, comprising providing a layer of fire resistant fibre blocks, eg.

rockwool fibre blocks, to form a support surface, optionally laying on the support surface one or more reinforcing bars or a reinforcing mesh, and casting onto the support surface a fire mortar as hereinbefore defined.

The fire mortars of the present invention can include an accelerator to accelerate the hardening of the cement.

In one embodiment, the fire mortar compositions can contain a mixture of accelerated and non-accelerated calcium aluminate cement. For example the accelerated calcium aluminate cement can be an accelerated form of Ciment Fondu Lafarge available from Lafarge Aluminous Cements of Grays, Essex, United Kingdom.

In a further aspect, the invention provides for the use of ceramic fibres in the manufacture of a fire mortar comprising a calcium aluminate cement.

The fire mortars of the present invention typically are formed by mixing a quantity or inorganic fibre with water and then adding the cement.

An advantage of the fire mortars of the present invention is that they possess not only good fire resistant properties, but also they are relatively light, yet are nevertheless load-bearing, which makes them ideally suited for use in the formation of suspended floors or ceilings.

Tests carried out on a 50mm thick slab of set fire mortar formed from a mixture of 70% ceramic fibre, 15% nonaccelerated Ciment Fondu Lafarge and 15% accelerated Ciment Fondu Lafarge illustrated that the slab can withstand temperatures of 12000C for in excess of two hours.

In a still further aspect, the invention provides a panel suitable, for example, for use in constructing a ceiling, wall or like structure, the panel comprising a pair of cover sheets and, disposed therebetween, a layer of fire mortar as hereinbefore defined.

In a preferred arrangement, there is provided a panel of the aforesaid type wherein a layer of intumescent material is interposed between the fire mortar layer and a cover sheet.

The panels of the invention can be constructed with dimensions broadly equivalent to conventional plasterboard sheet, and thus may be employed in place of plasterboard in, for example, the construction of ceilings and walls.

Typically, such panels can be of 9mm to about 30mm thickness. The cover sheets can be simply paper or cardboard layers of the type conventionally used in the facings of plasterboard.

The intumescent substance can be, for example, an alkali metal silicate or exfoliating graphite, and preferably it is exfoliating graphite.

The intumescent substance can be applied to the fire mortar layer before the fire mortar has set, such that it is firmly bonded thereto upon setting of the fire mortar.

Alternatively, or additionally, the intumescent substance can be mixed with a binder (e.g. a polyacrylate binder) to assist adhesion of the fire mortar layer to the intumescent substance, and adhesion of the intumescent substance to the cover layer.

One form of panel in accordance with the present invention is illustrated in Figure 1 which is a side sectional elevation through a portion of the panel.

As shown in Figure 1, the panel comprises a pair of covering layers of sheets 1 and 2 formed of card or a heavy duty paper material, between which are sandwiched a layer of fire mortar 3 of a composition substantially as described above, and an intumescent layer 4, which in this embodiment is formed of exfoliating graphite.

To prepare a panel of the aforesaid type, cover sheet 2 is supported on a suitable support surface (not shown) and a layer of fire mortar of the desired thickness is poured onto the sheet 2 whilst the mortar is still wet, exfoliating graphite is sprinkled onto the surface to the desired depth and the cover paper 1 is then applied. In order to ensure better adhesion, an aqueous solution or suspension of a binder (e.g. an acrylate binder) can be mixed with the exfoliating graphite and the resulting slurry poured onto the fire mortar layer 3 prior to applying the cover layer 1.

Tests carried out on a panel prepared as described above have shown that by incorporating a layer of intumescent material into the panel, the fire resistance of the panel is increased by several hours.

The example given above is by way of illustration only, and it will be apparent that numerous modifications and alterations could be made without to the illustrated without departing from the principles underlying this invention. All such modifications and alterations are intended to be embraced by this application.

Claims

1. A fire resistant mortar comprising a calcium aluminate cement and an inorganic fibre material.

2. A fire resistant mortar according to Claim 1 wherein the inorganic fibre material is a ceramic fibre, or a man-made mineral fibre.

3. A fire resistant mortar according to Claim 1 or Claim 2 wherein the mortar contains up to about 85% by weight inorganic fibre material.

4. A fire resistant mortar according to Claim 3 wherein the mortar contains between 60% and 80% by weight of the inorganic fibre material.

5. A fire resistant mortar according to any one of the preceding Claims wherein the inorganic fibre material is formulated together with a polymeric binder such as a polyacrylate or a polyvinyl acetate.

6. A fire resistant mortar according to any one of the preceding Claims wherein the calcium aluminate cement has a chemical composition corresponding to 38-40% A1203, 37-392 CaO, 3-5% SiO2 and 15-18% Fe2O3/FeO.

7. A fire resistant mortar according to Claim 6 wherein the cement contains a mixture of monocalcium aluminates, dicalcium silicate and calcium alumino ferrites.

8. A fire resistant mortar according to any one of the preceding Claims which includes an accelerator to accelerate the hardening of the cement.

9. A fire resistant mortar according to Claim 8 which contains a mixture of accelerated and non-accelerated calcium aluminate cements.

10. A lightweight load-bearing slab suitable for use as a flooring slab or a ceiling, said slab being cast from a fire resistant mortar according to any one of the preceding Claims.

11. A method of constructing a floor or ceiling slab, comprising providing a layer of fire resistant fibre blocks to form a support surface, optionally laying on the support surface one or more reinforcing bars or a reinforcing mesh, and casting on to the support surface a fire mortar as defined in any one of Claims 1 to 9.

12. The use of ceramic fibres for the manufacture of a fire mortar comprising a calcium aluminate cement.

13. A panel suitable for use in constructing a ceiling, wall or like structure, the panel comprising a pair of cover sheets and, disposed therebetween, a layer of fire resistant mortar as defined in any one of Claims 1 to 9.

14. A panel according to Claim 13 wherein a layer of intumescent material is interposed between the fire resistant mortar layer and a cover sheet.

15. A panel according to Claim 13 or Claim 14 which has a thickness of 9mm to about 30mm.

16. A panel according to Claim 14 in which the cover sheets are paper or cardboard layers of the type conventionally used in the facings of plasterboard.

17. A panel according to Claim 14 wherein the intumescent substance is an alkaline metal silicate or exfoliating graphite.

18. A panel substantially as described herein with reference to the accompanying drawings.