IE80585B1 - Intumescent and fire resistant compositions - Google Patents

Abstract

A particulate ceramic material containing at least 75% by weight of a non-fibrous ceramic shot material is used to make fire seals, fire barrier products and mortars. The fire-resistant mortars are particularly suitable for the preparation of light weight load-bearing slabs, for example flooring slabs or ceilings, and in the preparation of panels for use in the construction of ceilings and walls. The panels may optionally contain a layer of intumescent material.

Description

INTUMESCENT AND FIRE RESISTANT COMPOSITIONS The present invention relates to intumescent and fire- resistant compositions containing a ceramic material and to their use in, inter alia, the construction of flooring materials, and wall and ceiling panels, for buildings.

Our earlier British Patent Application No. 9207659.5 (Publication No. 2254609) describes the use of ceramic fibres in the preparation of intumescent and fire resistant products. Commercially available ceramic fibre of the type used in the process described in GB 2254609 contains a proportion of non-fibrous ceramic material in particulate form, which we refer to as shot. In processes such as the process described in GB 2254609, the particulate ceramic shot tends to become separated from the fibrous materials and accumulates as waste which is usually simply discarded. It has now been found that the ceramic shot material can be used in fireresistant compositions, and in certain instances is advantageous with regard to the ceramic fibre used hitherto.

Accordingly, the invention provides a fire-resistant mortar comprising a calcium aluminate cement and a particulate ceramic material containing at least 75% by weight of a non-fibrous ceramic shot material.

Preferably the ceramic particulate material contains at least 85% nonfibrous shot material, and more preferably contains at least 90% non-fibrous shot material.

The ceramic particulate material may contain up to 25% by weight of a fibrous ceramic material, preferably up to 15% by weight, and more preferably no more than 10% by weight ceramic fibrous material.

The ceramic fibrous materials from which the ceramic shot of the present invention is obtained are commercially available and typically comprise an alumina silicate material.

It is preferred that in relation to the total weight of the mixture of calcium aluminate cement and particulate ceramic material, the particulate ceramic material constitutes up to about 85% by weight, and more preferably between 60% and 80% by weight. Conversely, it is preferred that the calcium aluminate cement constitutes at least 15% by weight of the mixture and preferably between 20% and 30% by weight of the total weight of the mixture.

The fire-resistant mortar may be formulated together with a binder, for example a polymeric binder such as a polyacrylate or a polyvinyl acetate. The binder may be present in an amount of up to about 15% by weight relative to the total weight of the mixture of calcium aluminate cement and particulate ceramic material. Preferably the binder constitutes less than 10% by weight relative to the total weight of the said mixture, and more preferably no more than 5% by weight relative to the total weight of said mixture.

The calcium aluminate cements used in the fire-resistant mortars of the present invention are examples of high alumina cements and one particular high alumina cement is Ciment Fondu (Trade Mark) manufactured by the Lafarge Aluminous Cement Company of Grays, Essex, United Kingdom. The typical composition of a calcium aluminate cement, as determined by chemical analysis, can be 38-40% AI2O3, 37-39% CaO, 35% SiO2 and 15-18% Fe2O3/FeO.

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 m 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 a particulate ceramic material containing at least 75% by weight non-fibrous ceramic shot 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 of particulate ceramic material 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% particulate ceramic material, 15% non-accelerated Ciment Fondu Lafarge and 15% accelerated Ciment Fondu Lafarge illustrated that the slab can withstand temperatures of 1200°C for in excess of two hours.

A further advantage of the fire mortars of the invention is that they can be drilled more easily using conventional tools and thus panels made from the fire mortars can readily be fastened to other building components.

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 • 1 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 v 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 ί 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.

Claims (5)

1. A fire-resistant mortar comprising a calcium aluminate cement and a v particulate ceramic material containing at least 75% by weight of a non-fibrous ceramic shot material.

2. A fire-resistant mortar according to claim 1 wherein the ceramic particulate material contains at least 90% non-fibrous shot material.

3. A fire-resistant mortar according to claim 2 wherein the particulate ceramic material constitutes up to about 85% by weight of the total weight of the mixture of calcium aluminate cement and particulate ceramic material.

4. A fire-resistant mortar according to claim 3 wherein the particulate ceramic material constitutes between 60% and 80% by weight of the said total weight. 5. A fire-resistant mortar according to any one of claims 1 to 4 which contains a binder. 6. A fire-resistant mortar according to claim 5 wherein the binder is a polymeric binder. 7. A fire-resistant mortar according to claim 6 wherein the polymeric binder is a polyacrylate or a polyvinyl acetate binder. ( * 8. A fire-resistant mortar according to any one of claims 5 to 7 wherein the binder is present in an amount of up to about 15% by weight » relative to the total weight of the mixture of calcium aluminate cement and particulate ceramic material. 9. A fire-resistant mortar according to claim 8 wherein the binder constitutes less than 10% by weight relative to the said total weight. 10. A fire-resistant mortar according to any one of claims 1 to 9 wherein 5 the calcium aluminate cement has a composition, as determined by chemical analysis, of 38%-40% AI 2 O 3 , 37%-39% CaO, 3%-5% SiO 2 and 15%-18% Fe 2 O 3 -FeO. 11. A light weight load-bearing slab formed from a fire-resistant mortar as 10 defined in any one of claims 1 to 10. 12. 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 15 or a reinforcing mesh, and casting onto the support surface a fireresistant mortar as defined in any one of claims 1 to 10. 13. The use of a particulate ceramic material containing at least 75% by weight non-fibrous ceramic shot for the manufacture of a fire mortar 20 comprising a calcium aluminate cement. 14. 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 25 claims 1 to 10. 15. A panel according to claim 14 wherein a layer of intumescent material is interposed between the fire-resistant mortar layer and a cover sheet. 16. A panel as defined in either of claims 14 or 15 having a thickness in the range 9mm to about 30mm. Ί 17. A panel according to claim 15 or claim 16 wherein a layer of alkaline metal silicate or exfoliating graphite is interposed between the fire mortar layer and a cover sheet. *

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