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The principles behind producing bricks, pavers and clay roof tiles are similar
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.
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.
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.
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%.
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.
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
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.
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.