Construction – a new era
Innovations for the Future
Enhancing Concrete and Cement
Concrete is one of our most important construction materials. As hard and durable as rock, it is formed when water is added to cement, sand and gravel, and can be used for building strong foundations, tall skyscrapers and bridges with soaring arches. But concrete is also exposed to a number of environmental influences. Moisture attacks it, with sea water and road salt potentially causing irreversible damage. To prevent this, buildings, bridges near the coast, and road tunnels must have reliable protection from water.
Silicones play a significant role in sustainable construction, because they make cement and concrete water-repellent. “They’re suitable for more than just treating the surfaces of finished concrete parts. When used as additives in concrete and cement production, silicones protect the structures from within,” says Dr. Wei Cai, a construction materials expert who gives advice to cement and concrete manufacturers across the globe. Another advantage is that the addition of silicone also allows manufacturers of concrete to use lower-quality sand and gravel that can be sourced locally.
A silicone additive produced by WACKER is already used in India, the world’s second largest market for cement after China. Customers have used it to manufacture several million metric tons of water-repellent cement. “Plus, that cuts the electrical energy needed by up to 10 percent – another bonus in terms of sustainability,” says Dr. Abhijit Tarafdar, who developed the additive for Indian customers at the Amtala Competence Center. WACKER has also been exploring silicone additives in China, where another research laboratory for cement and concrete was opened in April 2019.
And on the other side of the globe, in Brazil, WACKER is likewise working to improve the quality of cement. “The composite cements used in Brazil are often blended with aggregates like fly ash and slag sand,” says Dr. Tobias Halbach, in charge of technology development for construction polymers at WACKER. This has an upside: it reduces the energy consumed during manufacturing, which, in turn, lowers CO2 emissions. The quality of the cement suffers, however. This cement can nevertheless be used with no drawbacks in dry-mix mortar applications thanks to dispersible polymer powders that WACKER has customized for the Brazilian market. These powders have been specially adapted to the regional variety of raw materials.
“Our products can therefore compensate for variations in the reactivity of composite cements and optimize the setting behavior. That lets our customers produce high-performance, long-lasting tile adhesives with local raw materials.”
– Dr. Tobias Halbach
Buildings: Hot off the Press
“Creating buildings through 3D printing is pretty popular right now,” explains Christophe Berset, who works in strategic marketing for construction polymers at WACKER. “The idea is that computer-controlled production methods make a variety of shapes feasible and cost-effective to manufacture.” A 3D printer applies liquid mortar through a nozzle one layer at a time, after which the mortar sets and forms a stable plastic object. Berset and his colleagues, in partnership with the Technical University of Munich and Nanyang Technological University in Singapore, are working together to optimize how polymers can increase the printed material’s durability and mechanical properties.
The key difficulty lies in finding the right balance between the flow characteristics of the mortar and its setting speed. “The compound has to be a liquid that’s easy to pump when it’s in the printer tubing, but then when you apply it, it has to modify its rheology quickly so that the layers remain stable,” says Berset. “Our formulations can already do that really well.” The team is currently working on producing a variety of mortar formulations for producing high-quality, printed elements.
Building Is Going Modular
Demand for affordable housing is growing – especially in cities. A rise in construction costs, however, has led to a shortage of new or existing buildings in the affordable and mid-range price brackets. Modular construction is one solution to this problem. The approach involves prefabricating sections of buildings or even entire residential units, and then simply assembling them on site. “Wall elements, including windows and insulating layers, even entire rooms – bathrooms, for example – can be prefabricated,” explains Christophe Berset, who works in strategic marketing for construction polymers at WACKER. “The tiles, shower, and toilet are already installed in the wet rooms, which arrive at the construction site ready to plug in, as it were.”
When these kinds of units are mass produced, economies of scale come into play, significantly reducing production costs and hours worked on site. According to a McKinsey study, modular construction reduces costs by up to 20 percent and can cut construction time in half. There are challenges, however.
“Transporting the finished units produces an enormous amount of vibration. But our polymers lend tile adhesives, self-leveling flooring compounds and composite materials a degree of flexibility. Not only do the various modules arrive at the construction site undamaged – they also remain intact over the long term.”
– Christophe Berset
Assembling elements like these has now become daily routine at many construction sites. Silicones and hybrid polymers play an important role in that, delivering a permanent bond for joints and walls. “As flexible sealants, they also balance the forces acting on the materials. That prevents cracks from forming due to seasonal temperature fluctuations,” says Dr. Arndt Schlosser, responsible at WACKER for sealant and adhesive applications in the construction industry. “That keeps water from penetrating modular buildings so that they last a long time.”
Another advantage is that no damage is done to the insulating layers of wall elements joined in this way. “But when you drill holes and screw in bolts, you generate cold bridging, and that compromises the thermal insulation,” he says, noting that WACKER has the modular construction trend firmly in its sights: “We watch the market very closely so that we can align our product development as much as possible with challenges in the industry,” he adds in summary.
Recycling in Construction
Sustainability is also the theme underlying the establishment of a shared innovation platform with the Karlsruhe Institute of Technology (KIT). WACKER is participating in this platform to foster dialogue among specialists about sustainable construction throughout the entire supply chain.
The chemical company is also supporting the modernization and expansion of the KIT Material Library. The focus is on sustainable construction techniques using digitalized exhibits, for instance those made of recycled material (such as tiles), recycled glass or construction materials made of recycled paper or plastic. The library also serves as a source of information and ideas for use in developing new technologies in joint research projects in which renewable resources or recycled materials can be meaningfully combined and upgraded with polymers or silicones from WACKER.
Sustainable Cities
WACKER has been cooperating with Singapore-ETH Centre’s Future Cities Laboratory (FCL) since 2017. The cooperation focuses on how construction materials can be designed to be more sustainable for cities of the future. The spotlight is on functional polymers for enhancing renewable, locally available construction-sector raw materials. For example, WACKER and FCL experts are examining how they can use construction chemicals to make bamboo even more effective, viable and durable.
A future research project takes a similar approach: renewable mycelium-based materials will be refined for use in innovative building elements.
