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Resource Efficiency

The Enduring City

Concrete is used in construction more than any other material in the world. Construction-chemical additives and Protectosil® building-protection agents from Evonik turn this gray artificial stone into a high-performance material.

Many buildings throughout the world have an invisible, permanent shield protecting them from damage caused by moisture penetration and environmental influences—examples include the world-famous Sydney Opera House, Times Square in New York, and the 36 km Hangzhou Bay Bridge in China.

Deep impregnation with silanes has been used as a way of protecting structures for many decades now. While the products are designed for hydrophobization, protecting surfaces, and combating graffiti and corrosion, they can also be used for reinforcing stone. Protectosil® protects mineral-based substrates like concrete, clinker brick, natural stone, and much more, preventing water and the pollutants dissolved in it from penetrating the building fabric. Protectosil® provides all-round, long-term protection for buildings, both historical and modern, and for infrastructure—and installation time is minimal, thereby limiting the time a building is unavailable for use and greatly reducing energy and maintenance costs.

In addition, Evonik’s building-protection products and defoamers can also be used directly in the production of concrete. Air-entraining agents optimize the control that manufacturers have over the size, distribution, and quantity of entrapped air. This plays a critical role in enabling concrete to bear weight, in lending it the necessary mechanical properties, and in providing long-term protection from damage due to freeze-thaw cycles. When mixed directly into the concrete, TEGOSIVIN® hydrophobizing agents based on alkoxy-functional silanes and siloxanes can provide additional protection and ensure water resistance. When cement or concrete harden, their volume changes—they shrink. Shrinkage reducers like SITREN® SRA reduce inner tension within the pore structure of the concrete, lower the capillary pressure, and optimize water content. The result is an unusually dense matrix that prevents cracks from forming during drying, thus increasing the longevity of the structure.

The idea of giving concrete the ability to heal itself takes this one step further. Evonik scientists working on the Wallcraft project are developing a product additive that will extend the life of concrete—when cracks form, they trigger the additive to fill in the resulting fissure.