GB1580118A - Glass bricks - Google Patents

Description

(54) GLASS BRICKS (71) WE, COMPAGNIE INTERNA TIONALE DE MINERALLURGIE CIM, a Body Corporate organised under the laws of the French Republic, of 63, rue de Villiers, F92200 Neuilly Sur Seine, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to glass bricks having improved fireproofing properties.

There are known hollow bricks of glass formed of two half bricks which are themselves hollow and connected together by fusion, welding or adhesion to form the brick. There are also known similar bricks containing an insert sheet of glass parallel to faces of the brick and dividing the interior cavity in two. This insert sheet generally serves to colour the brick to improve its acoustic and heat insulating properties.

French Patent 848,079 describes such a brick. To avoid stresses between the insert glass sheet and the brick itself this sheet is not welded or adhered to the brick but it rests freely in a V shaped hollow formed in the four lateral walls of the jointing of the two half bricks or in an open groove directed towards the interior of the brick at the join of the two half-bricks. The bricks which have been made up to now are generally of sodium calcium glass which is generally re-fired. They are used individually or may be assembled in panels with joints of adhesive or cement and mounted in walls to form translucid walls or wall elements.

Such bricks are flame-proof for two hours, that is to say they remain in place for two hours preventing any transmission of smoke or gas through the wall which they form and are fireproof for a quarter of an hour, that is to say during this lapse of time they provide a barrier not only to flames and gas but also to heat so that the temperature on their face remote from the fire does not exceed 140"C.

In a fire such bricks behave in the following manner.

In the first few minutes of the fire, by thermal shock, the faces of the bricks facing the fire and remote from the fire, become cracked. Ibe bricks held by cement which surrounds them remain in place and continue to prevent gas and smoke passing through, the width of the cracks being too small. After ten or fifteen minutes the glass is softened and the cracks open. The brick continues to play its role as a screen against smoke and gas up to the start of fusion of the glass which shows itself in liquid flow after about two hours of fire. The bricks remaining transparent, the radiated heat raises the temperature of the face remote from the fire and any object placed behind it so that after only a quarter of an hour the temperature limit of 140"C required for a product to qualify as fire-proof is exceeded.

The present invention is intended to improve the resistance to fire of glass bricks and more especially to improve their fireproofing qualities.

According to one aspect of the invention there is provided a hollow glass brick formed of two hollow half bricks joined together and an insert wall mounted freely inside and extending parallel to faces of the brick separating the brick into two compartments,the insert wall being of glass convertible by heating to vitro-ceramic material.

The insert wall is "mounted freely", i.e. it is neither welded nor adhered to the two half bricks. It may rest in a generally V-shaped hollow formed in the four lateral walls of the brick at the join of the two half bricks or in an open groove directed towards the interior of the brick provided at the joint of said half bricks.

Suitably, the glass convertible by heating has the following constituents in percentage by weight: SiO2/58, CaO/18, Al203/6,MgO/4.5, Na2O/ 5, K2O/3.75, F/8, Fe203/0.095.

In one embodiment the two half bricks are of conventional glass such as sodium calcium glass which has generally been annealed whereas the insert wall is of glass convertible by heating to vitro-ceramic material which glass has not been subjected to heat treatment which would cause devitrification. The insert wall may be reinforced with metal mesh or tempered in air, oil or chemically.

In a second embodiment the two half bricks are of a glass convertible by heating to vitroceramic material and the insert wall is also convertible by heating to vitroceramic material. This insert wall may be reinforced with metal mesh or tempered in air, in oil or chemically.

In a third embodiment the two half bricks are of glass convertible by heating to vitroceramic material, tempered in air, oil or chemically and the insert wall is also of glass convertible by heating to vitroceramic material which is reinforced with metal mesh or tempered in air, oil or chemically.

The manner in which the bricks behave when exposed to fire will now be described.

At the start of the fire the face of the brick facing the fire is first subjected t9 thermal shock and is rapidly cracked. However the pieces of glass remain in place because of the binding effect produced by the cement and because they are held by the other part of the brick which is not yet cracked.In the cases where, as in the first two embodiments described, the glass forming the brick is not tempered, this cracking is produced in the first five minutes as the difference in temperature between the edges (which remain cooler) and the centre of the face is about 50"C. When, as in the third embodiment, the glass of the two half bricks is tempered, the cracking is produced later at a temperature difference of about 200"C. When the glass is tempered the cracking produces an expansion of the brick, an expansion which increases even more the binding effect and which allows even bricks of large dimensions to remain in place after cracking.The face of the brick subjected to fire is thus held in place and protects the other walls of the brick, until the glass reaches the temperature of softening and melts and flows, unless it is a glass of vitro ceramic composition as in the second and third embodiments mentioned above. In this case under the effect of high temperature, crystallisation is produced. As crystallisation advances the wall becomes opaque, thus providing a radiation barrier. The crystallised glass remains in place for the whole duration of the fire.

Over a certain time while protected by the forward face of the brick, the insert wall is subjected to heating due to the fire. Being freely positioned inside the brick and subjected to a rise in temperature, less sudden than the face of the brick, this insert wall resists the increase in temperature for a longer period. When it is not tempered but only reinforced it cracks nevertheless, but the pieces remain held in place by the reinforcement. The insert wall, whether it is cracked but reinforced or tempered, remains in place until the glass forming it becomes soft. The edges of the insert wall become welded to the lateral walls of the brick, thus ensuring imperviosity which shows itself especially in the case when the brick itself is not of vitro-ceramic material or where the glass forming it melts or flows.

The glass of this insert wall devitrifies and crystallises as the temperature rises. Simultaneously this wall becomes opaque, reducing considerably the transmission of thermal radiation. The glass, once transformed into vitro ceramic, will be able to resist heat for the duration of the fire.

In a variant of the second and third embodiments only a half of the brick is of glass convertible by heating to a vitroceramic material; this half should be situated on the side of the structure where fire is likely to be produced.

'The above embodiments can thus povide 1, 2 or 3 walls which permanently resist fire: - 1 wall (when only the insert wall is of glass convertible by heating to a vitroceramic material); - 2 walls (when one half brick and the insert wall are of glass convertible by heating to a vitro-ceramic material); - 3 walls (when the entire brick and the insert wall are of glass convertible by heating to a vitro-ceramic material.

Embodiments of the invention will be described in the following Examples, given by way of illustration.

Example 1 There were made two hollow half bricks of sodium calcium glass and the half bricks were welded together to form a hollow brick.

An insert was placed inside the brick before welding of the two half bricks. This insert was a sheet of ceramisable glass, i.e.

glass convertible by heating to a vitroceramic material, of 6 mm thickness, reinforced with half-inch steel mesh.

The material forming the insert wall had constituents selected from the following: SiO2, CaO, Awl203, MgO, Na2O, K2O, F, Fe2O3, B203, ZnO, Li2O, S2, ZrO2, TiO2, RbO2 Example 2 There were made two half bricks of ceramisable glass which had not been subjected to ceramisation heat treatment. Before their welding to form a brick, there was introduced an insert wall, also of ceramisable glass material, previously tempered.

The brick and the wall had the same composition as the insert wall material specified in Example 1.

Example 3 There were used two half bricks of ceramisable glass which had not been subjected to ceramisation heat treatment.

This glass had the same composition as the glass of Example 1.

Before welding together of the two half bricks, there was introduced an insert wall of 6 mm thickness, reinforced with half-inch steel mesh of another ceramisable glass which had not been ceramised having the following composition in percentages by weight: SiO2/58, CaO/18, Al203/6, MgO/4.5, Na2O/5, K2O/3.75, F/8, Fe203/0.095.

On exposure to fire, cracking was completed at a temperature of 419"C on the side exposed to fire.

The start of ceramisation for the insert wall came about at a temperature measured on the surface of the insert wall remote from the fire of 640"C.

The cracks started to close at the same temperature of 640"C. Opacity then started to develop, at 698"C the cracks were completely closed, at 750"C ceramisation was complete.

Instead of being welded the two half bricks may be adhered cold, e.g. with an epoxy adhesive or silicone adhesive.

WHAT WE CLAIM IS: 1. A hollow glass brick formed of two hollow half bricks joined together and an insert wall mounted freely inside and extending parallel to faces of the btick separating the brick into two compartments, the insert wall being of glass convertible by heating to vitro-ceramic material.

2. A glass brick according to claim 1 in which the insert wall is reinforced with metal mesh.

3. A glass brick according to claim 1, in which the inset wall is of tempered glass.

4. A glass brick according to claim 2 or 3, in which at least one of the half bricks forming the brick is of glass convertible by heating to vitro-ceramic material.

5. A glass brick according to any one of the preceding claims, in which at least one of the half bricks forming the brick is of tempered glass.

6. A glass brick according to any one of the preceding claims, in which the glass convertible by heating has the following constituents in percentages by weight: SiO2/58, CaO/18, Al203/6, MgO/4.5, Na2O/5, K2O/3 .75, F/8, Fe203/0.095.

7. A glass brick, substantially as hereinbefore described with reference to the foregoing Examples.

8. A wall or wall element, comprising glass bricks according to any preceding

Claims (1)

1. claim.