GB2045675A

GB2045675A - >Preventing distortion when making panels

Info

Publication number: GB2045675A
Application number: GB8009917A
Authority: GB
Original assignee: Ibstock Building Products Ltd
Current assignee: Ibstock Building Products Ltd
Priority date: 1979-03-27
Filing date: 1980-03-24
Publication date: 1980-11-05

Abstract

The invention relates to a method of producing a preformed building panel comprising a main backing portion (10) of glass-reinforced cementitious material having a plurality of facing units (4) of brick or tile supported at a front face thereof, comprising the steps of placing the facing units (4) in a mould frame, inserting mortar or other suitable adhesive in a plastic condition between mutually confronting surfaces of said units and then applying a cementitious mouldable material (10) containing glass reinforcement fibres into the mould or frame so as to form said backing portion, in a manner so as to provide, around the marginal portions of the rear surface of the panel, a reinforcing flange (12) or other ridge-like formation of cementitious material, in order to minimise the effect of the difference in the shrinkage rate of a rear surface of the backing portion relative to that of the front surface thereof. The area between the flanges is left unfilled, or further coating layers (16, 18) may be provided, of polystyrene and cementitious material, to a thickness which brings the coatings to a level substantially even with the lip of the flange 12. <IMAGE>

Description

SPECIFICATION Improvements in or relating to preformed building panels The invention is concerned with improvements in or relating to preformed building panels, in particular panels comprising facing units of brick or tile having a main backing member of glass-reinforced cementitious material.

It is well known to produce building panels which comprise for example, brick facing units with a backing of for example, reinforced concrete. In order to overcome the handling problems associated with the weight of such panels, it has been proposed to use brick-faced panels of glass-reinforced cement or cementitious material. Nevertheless problems arise with the manufacture of such panels, notably distortion and bowing of the panels.

Differences in shrinkage rate, with consquent distortion of the panel, occur because of the drying out of the cementitious material.

It will be understood that little reduction in overall dimension of the front face can occur because of the presence of the bricks or tiles, but that the effect of the natural shrinkage of the cementitious material must be limited so that the panel remains flat.

The invention sets out to minimise this problem The invention provides a method of producing a preformed building panel comprising a main backing portion of glass-reinforced cementitious material having a plurality of facing units of brick or tile supported at a front face thereof, comprising the steps of placing the facing units in a mould frame, inserting mortar or other suitable adhesive in a plastic condition between mutually confronting surfaces of said units and then applying a cementitious mouldable material containing glass reinforcement fibres into the mould or frame so as to form said backing portion, in a manner so as to provide, around the marginal portions of the rear surface of the panel, a reinforcing flange or other ridge-like formation of cementitious material, in order to minimise the effect of the difference in the shrinkage rate of a rear surface of the backing portion relative to that of the front surface thereof.

In one example of the invention, the ridge stands proud around the perimeter of the rear surface of the backing portion. In another example the backing portion may be coated with a further layer, which may comprise a cement/sand mix including lightweight insulating material such as polystyrene, and a finishing layer of cementitious mouldable material containing glass reinforcement fibres may then be applied to a level even or substantially even with the lip of the flange.

There will now be given example of the manufacture of panels according to the invention. It will be understood that the description, which is to be read with referrence to the accompanying drawings, is given by way of example only and not by way of limitation.

In the drawings: Figure 1 shows a fragmentary. cross-sectional view of a first example of a panel produced according to the invention; and Figure 2 shows a similar cross-sectional view of a second example of a panel also produced according to the invention.

Fig. 1 shows a preformed panel 2, comprising a plurality of facing units 4 arranged in a regular pattern. Gaps 6 between the units are filled by narrow fillets of mortar, and the appearance of the resulting visual surface is closely similar to a conventionally constructed wall, since in the present example the facing units are brick slips. The facing units 4 have a backing portion 8 formed from an insitu moulded glass fibre-reinforced cement/sand mixture. The backing portion comprises a main layer 10 of this mixture around the marginal portion of which is formed a ridge 12.

Fig. 2 shows a panel 1 4 which is similar in construction to the panel shown in Fig. 1 and like parts of the Figures are given the same reference numerals. However, the panel 14 has the additional features of a layer 1 6 of a cement/sand mixture which includes a light weight insulating material. In the present example, a material marketed under the trade name "Styropor" is used which comprises cement, sand and expanded polystyrene beads. A final layer 1 8 of glass fibre reinforced cement/sand mixture is then applied to a layer even with the lip of the ridge 1 2.

The method of producing the panels is described below.

EXAMPLE I In the manufacture of the panel 2 as shown in Fig. 1, a number of brick slips 4 were placed face-down in a mould frame in the desired pattern and a plastic mortar mix was introduced between gaps 6 left between the slips by suitable means, for example a mortar gun, taking care to avoid spillage of mortar on the rear, upwardly facing, surface of the slips.

The brick slips had a high water-absorption capacity in the region of 22% by weight.

The next step, that of applying the material of the backing portion 8, was then carried out while the mortar was still in a plastic state, and comprised applying cement mixed with sand in a 2:1 ratio by weight in wet mix.

Glass fibre was spread throughout the applied mix in an amount of approximately 5-6% of the total weight and to a thickness of approximately 20 mm over the main portion 10 of the panel area, with the ridge 1 2 formed around marginal portions of the area to an additional thickness of 60 mm.

The panel 2 was allowed to harden and was then de-moulded. After the materials had fully dried, the panel was inspected, and little or no distortion was observed after several weeks had elapsed.

EXAMPLE 11 In the manufacture of the panel 1 4 as shown in Fig. 2, a number of brick slips 4 having a 7% water absorption capacity were placed in a mould frame and mortar applied as in Example 1.

Glass-fibre reinforced cement mix was then applied in a 20 mm layer 8 in the same manner as before, forming the ridge 1 2. A 40 mm layer 1 6 of the proprietary product "Styr opor was then poured onto the layer 8.

A second layer 1 8 of glass-reinforced cement/sand mix was then applied on top of the "Styropor" to a depth of 20 mm. The intermediate layer of "Styropor" acted as an additional reinforcement and the final panel suffered a negligible amount of distortion.

Claims

1. A method of producing a preformed building panel comprising a main backing portion of glass-reinforced cementitious material having a plurality of facing units of brick or tile supported at a front face thereof, comprising the steps of placing the facing units in a mould frame, inserting mortar or other suitable adhesive in a plastic condition between mutually confronting surfaces of said units and then applying a cementitious mouldable material containing glass-reinforcement fibres into the mould or frame so as to form said backing portion, in a manner so as to provide, around the marginal portions of the rear surface of the panel, a reinforcing flange or other ridge-like formation of cementitious material in order to minimise the effect of the difference in the shrinkage rate of a rear surface of the backing portion relative to that of the front surface thereof.

2. A method as claimed in claim 1, wherein the layer of cementitious mouldable material forming the main backing portion is applied while the mortar or other adhesive is still in a plastic condition.

3. A method as claimed in claim 2, wherein the cementitious material is a ce ment/sand mix which is applied to the rear surface of the facing units, glass fibre reinforcement material being then spread over and entrained with the cement/sand mix.

4. A method as claimed in any one of the previous claims, wherein the cement/sand mix contains these materials in a 2:1 ratio by weight and the glass fibre is introduced in an amount in the region of 5-6% of the total weight of the reinforced mix.

5. A method as claimed in any one of the preceding claims wherein at least one further layer of cementitious material is applied to the main backing portion.

6. A method as claimed in claim 5, wherein one of said further layers comprises a cement/sand mixture containing a lightweight insulating material.

7. A method as claimed in claim 6 wherein said cement/sand mixture contains expanded polystyrene beads.

8. A method as claimed in either one of claims 7 and 8, wherein a final layer of glassreinforced cementitious material is applied to the cement/sand layer to a level even with an outer lip of the ridge formed on the main backing portion.

9. A method of producing a preformed building panel, substantial as hereinbefore described with reference to (a) Fig. 1, (b) Fig. 2 of the accompanying drawings.

10. A preformed building panel produced according to the method of claim 1, constructed and arranged substantially as hereinbefore described with reference to and as shown in Fig. 1 of the accompanying drawings.

11. A preformed building panel produced according to the method of claim 5, constructed and arranged substantially as hereinbefore described with reference to and as shown in Fig. 2 of the accompanying drawings.