Production process

Clay pit at production facility Lantenne — © Uwe Strasser

Raw materials management

Clay blocks, facing bricks, roof tiles

The most important raw material for our ceramic products (clay blocks, facing bricks, roof tiles) is clay, a recyclable natural resource. We attach great importance to the greatest possible conservation of resources in clay extraction and the expert restoration of former clay mining sites.

Clay is extracted from the clay pit using modern equipment and subsequently transported to the clay preparation plant. Since the clay pits are usually located close to our production facilities, transport routes are short.

Clay extraction on the Lantenne site to produce Koramic tiles. — © Grégory TACHET

Preparation

After extraction, the clay is prepared in a grinding and milling process

After extraction, the clay is prepared in a grinding and milling process, foreign materials such as stones are removed to achieve the right consistency and homogeneity of the clay required for production. Water, sand and, for some products, pore-forming agents are then added.

Production plant Ewhurst, UK — © Uwe Strasser

Shaping

Ready for shaping

After a brief storage period in a mud house, the clay is ready for shaping. It is pressed into the desired shape through extrusion dies and subsequently cut into individual bricks or compressed in moulds by automatic presses.

For roof tiles we have developed our own special tile moulds and die moulds, which are the basis of innovative products providing new shapes as well as optimised product features.

Dried clay block piles on kiln car on their way to the kiln — © Uwe Strasser

Drying

More efficient drying technologies

The shaped products are then stacked on pallets and transported to the dryer. The drying process prepares the bricks for firing by extracting moisture from the soft "green" bricks. New and more efficient drying technologies such as the low-temperature dryer have reduced the drying period to one-third of the originally required time. Depending on the type of product, the drying period lasts between four and 45 hours. During this time, the moisture content drops to below 2%.

Glazed street roof tile transport — © Wienerberger AG

Colouring for clay roof tiles only

Dip coated or glazed

After the drying process, clay roof tiles are either engobed (dip coated) or glazed, unless they remain natural red. Engobed clay roof tiles have matt, matt-glossy or glossy surfaces. There are different ways of applying engobes: by dipping, dousing, centrifugal casting or spraying the still unfired clay tile. Glazed tiles are covered with a very hard layer that closes all pores and makes the tile extremely water-resistant. At the same time, this layer of glaze gives the tile its special shiny look.

Firing

Fired over a period of 6 to 36 hours

After drying, the products are transferred to a kiln, where they are fired over a period of six to 36 hours. Firing gives the products a durable strength and makes them permanently non-flammable and fire-proof.

Wienerberger engineers are continuously working on reducing the energy consumption of the drying and firing process. Kiln and firing technologies as well as airstream systems have reduced the required firing time by up to two-thirds in recent years. Additionally, the residual heat from the cooling process is recovered and recycled in the drying process.

Packaging and delivery

Quality inspection

After the fired products have cooled down, they pass a quality inspection in our laboratories. For the packaging of our products we use particularly thin foils.

Wienerberger production plant Beerse — © Uwe Strasser

Transport

Decentralised network of plants

Transport routes to our customers are short because of our regional, decentralised network of plants, which also reduces the impact of our business operations on the environment.

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