Belgian Blue Limestone from Carrières du Hainaut Used in Osaka, Abu Dhabi, and New York

Until October 13, the World Expo in Osaka, Japan, is in full swing. Several Walloon companies have contributed to the success of the Belgian pavilion and its surroundings. This includes Carrières du Hainaut and Carrières de la Pierre Bleue Belge, which supplied blue limestone for the pavilion’s outdoor areas. Let’s take a closer look.

Belgian blue limestone is renowned worldwide. It has been used for the restoration of the interior floor of Notre-Dame Cathedral in Paris, in a New York City subway station, at the Louvre Museum in Abu Dhabi, and now around the Belgian pavilion at the Osaka World Expo.

These achievements belong to the Walloon company Carrières du Hainaut. Founded in 1888, the company has over 135 years of expertise. “At the beginning of the last century, there were about thirty small family-run quarries on the territories of Écaussinnes and Soignies. Today, only two remain: us and our competitors, located just 3 km away as the crow flies,” explains Philippe Séquaris, Architect and Product Manager.

For the construction of the Belgian pavilion in Osaka, Carrières du Hainaut was approached by the consortium in charge of the project to supply Belgian blue limestone for the pavilion’s exterior. “The theme of the pavilion revolves around water. Our stone fits perfectly with this theme since it originates from a tropical sea 350 million years ago. Through successive sedimentation, layers formed the rock known today as Belgian blue limestone or Petit Granit,” explains Philippe Séquaris.

For this project, Carrières du Hainaut chose to collaborate with their competitor, Carrières de la Pierre Bleue Belge. “This is a showcase for Belgium and more specifically for Soignies’ expertise. Visitors walk on blue limestone that comes from Soignies,” he adds. Two different finishes were selected for the pavilion’s surroundings, with each quarry supplying the stones for one of the requested finishes.

Carrières du Hainaut has worked on many emblematic international projects, such as the interior fittings (floors and display areas) of the Louvre Museum in Abu Dhabi. More recently, they contributed to the redevelopment and renovation of Penn Station in New York, including its esplanade. They were also involved in the restoration of Notre-Dame Cathedral in Paris. “Projects abroad like these are fairly occasional,” notes Philippe Séquaris. Carrières du Hainaut has also been commissioned by luxury brands such as Hermès, which created small coffee tables from the company’s blue limestone.

Seventy percent of Carrières du Hainaut’s turnover comes from Belgium. On the one hand, they sell stone to stonemasons and marble workers, who transform the slabs into window sills, kitchen countertops, mailboxes, and more. On the other hand, the blue limestone is widely used in public development projects in Belgium. “It’s used for roads, public squares, public buildings. These come through public procurement contracts,” adds Séquaris. Notable examples include Hall 5 of the Heysel and the Cinquantenaire arcades in Brussels, both built with stone from Carrières du Hainaut.

The remaining turnover comes from exports, mainly to France, the Netherlands, and Germany.

The qualities of blue limestone

Compared to other stones, blue limestone has numerous qualities. “It has excellent compressive strength. Since the Middle Ages, it has been used for its ability to withstand compression, allowing builders to stack stones and create structural columns for religious buildings. Another advantage is that it is a workable stone for sculpting. In addition, blue limestone is low in porosity, making it suitable for all kinds of climates,” explains Philippe Séquaris.

Blue limestone is also recyclable. “Our CO₂ impact is almost zero compared to other construction materials. Producing a ceramic tile, for example, requires and consumes an enormous amount of energy. When you compare the lifecycle of a building, our CO₂ impact is virtually nil. Another advantage is that the material can have a second or even third life,” he adds. Large stones can be cut into smaller slabs, and if they are no longer usable, they can be transformed into aggregates.

Isabelle Anneet (AWEX)