Glass Bricks in Buildings: Increased Scope..!

Glass works were once used with ornamental value in a building and of course, glass bricks were being used mainly in industrial units. But nowadays the fixing of these blocks is being done in resi­dential and commercial buildings with a purpose of bringing natural light into the building.

Glass bricks are architectural ele­ment made from glass. Also known as glass blocks, these bricks provide visual obscuration while admitting light.

The glass block was originally developed in the early 1900s to pro­vide natural light in manufacturing plants. Now these are produced for both wall and floor applications.

aMaking of glass bricks / blocks..!

Glass blocks for use in floors are normally manufactured as a single solid piece, or / as a hollow glass block with thicker side walls than the standard wall blocks. These blocks are normally cast into a reinforced concrete grid - work or set into a metal frame, allowing multiple units to be combined to span over openings in basements & roofs.

Glass wall blocks should not be used in flooring applications. Hol­low glass wall blocks are manufac­tured as two separate hemispheres and, whilst the glass is still molten, the two hemispheres are pressed together and annealed. The result­ing glass blocks will have a partial vacuum at the hollow centre.

aSpecialist glass blocks..!

These are produced for various ap­plications including fire resistance, and bullet & vandal resistance: These blocks are generally solid glass or / have very thick side walls similar to pavement blocks.

Fire resistance of varying degrees can be achieved by several methods. Standard production hollow wall block will offer little fire resistance. However, resistance is improved by utilising specially produced hollow blocks with thicker sidewalls, or the inclusion of a special layer of fire resisting material between the two hemispheres of the block during manufacture.

Some manufacturers of glass blocks have developed a method of bonding two glass blocks together with adhesive, producing blocks of up to 160 mm or 6½ inches thick with enhanced fire resistance. It is important that the block manu­facturer’s recommendations are followed with regards to the instal­lation of fire resisting glass block walls, as without special construc­tion techniques, the wall will not achieve the desired fire resistance.

A recent innovation in the manu­facture of glass blocks is the inclu­sion of argon gas within the hollow centre of glass wall blocks. This advancement in production tech­nique has resulted in a glass block which is able to offer significantly improved thermal insulation proper­ties.

a Global Standards..!

Glass blocks in Europe are manu­factured in accordance with the European Standard EN 1052-2. The International Standard is ISO TC 160 / SG1.

The Standards allow for variation in sizes and production irregularity. Blocks fall within three classifica­tions - Class1, Class 2 and Class 3 - with Class 1 being the highest and best rating with a maximum permis­sible deviation from designed size and rectangularity of 1 mm.

Some hollow glass wall blocks are available in coloured variants. These coloured variants fall into two categories; those that are manu­factured with coloured glass which are UV stable and can be used in the same locations as standard clear glass blocks.

The other method by which col­oured glass blocks are achieved is to inject a coloured material, dye or transparent paint into the hol­low centre of the blocks to form a permanent coating. This method of producing coloured blocks ena­bles vibrant colours to be achieved which are not possible with col­oured glass. The downside of this production method is that the col­oured coating may not be UV stable and can fade in bright sunshine over time and may therefore, not be suit­able for all locations.

aFixing glass blocks..!

Glass wall blocks are fixed together to form complete walls by several methods – the most common method of construction is to bed the blocks together in a Portland cement-based mortar with reinforcing rods of steel placed within the mortar as recommended by the project architect or block manufacturer.

Other methods of construction include several proprietary systems whereby the mortar is replaced by timber or PVC extrusions.

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