Saint-Savin is located between Lyon and the Alps and has just over 4,000 inhabitants. Ytong AAC has been produced here since 1989. While one-third of the autoclaved aerated concrete produced by Xella in France is sold under the Siporex brand in DIY stores, two-thirds is sold under the Ytong brand through building materials retailers. This approach helped stabilize sales, especially during the corona pandemic, as construction work was suspended in many places and AAC is still a niche product in France.
 
A role model in ESG
 
At the Saint-Savin plant, 32 employees work in three shifts to produce around 540 m³ of autoclaved aerated concrete per day. The Saint-Savin site is a real role model in the area of corporate social responsibility, for example in occupational safety: there has not been a single occupational accident here for several years. In addition, to improve employees' professional development opportunities and expertise, the number of annual training hours is to be increased by 10% by 2025. In addition, the plant has developed a process for recycling the powder residues remaining from production. For this purpose, it was necessary to modify the AAC formulation and set up appropriate equipment. Three years ago, a robot-assisted line for the production of U-blocks was installed. When the blocks were hollowed out, considerable powder residues were produced there during production, and so the question arose as to whether these residues could be recycled instead of being disposed of.
 

Improved sustainability through innovative ideas

An internal team then developed a new formulation that would allow the powder to be recycled. The result was a process that today allows a significant proportion of the sand normally used in the composition of AAC to be replaced by the powder residues. To achieve this, 180,000 euros had to be invested in the equipment for recovering, screening and transporting the powder to the concrete mixing plant. "The volumes are significant, potentially 2,000 tons of powder per year. In addition, the introduction of this process has reduced the amount of sand required to produce AAC by 8%. As a result, we save one of the ten trucks that travel back and forth between the plant and the quarry every day, while also extending the useful life of the quarry. Sand extraction plays an important role in our business. It therefore makes sense to look for solutions to use as little sand as possible without compromising the quality of our products," explains Sébastien Ray, manager of the Saint-Savin plant. "At the same time, we save energy because, unlike sand, the powder is already crushed. The positive impact on the safety of the handling and transport teams is also considerable. Ultimately, we turned a limitation into an opportunity, and I'm proud that we were able to develop this great solution ourselves. In addition, recycling means we have to transport less sand, which reduces the impact on air quality in our region," continues Sébastien Ray.

However, this was only the first step in the improvement process. By investing an additional €1.1 million, the plant management has further optimized waste recycling. To achieve further improvements, a new shredding and screening machine is now located just outside the plant. "By taking this step to conserve natural resources, Xella aims to save 350,000 euros a year. Half of the offcuts are processed into powder and crushed material. The recycling of our waste - 50 tons of powder and 25 tons of crushed material - is done entirely in-house. In addition to a new processing line, this also required the construction of storage silos and a new transport system. The new plant pays for itself through the savings made possible by replacing sand and reducing the number of transports," says Sébastien Ray.

All the autoclaved aerated concrete powder produced at the plant is recycled and now replaces up to 20% of the sand used in production instead of just 8%.