• By using a carbonated -- rather than a still -- water-based solution during the concrete manufacturing process, a Northwestern University-led team of engineers has discovered a new way to store carbon dioxide (CO₂) in the ubiquitous construction material.
• Not only could the new process help sequester CO₂ from the ever-warming atmosphere, it also results in concrete with uncompromised strength and durability.
• "The cement and concrete industries significantly contribute to human-caused CO₂ emissions,"
• instead of injecting CO₂ while mixing all the ingredients together, they first injected CO₂ gas into water mixed with a small amount of cement powder. After mixing this carbonated suspension with the rest of the cement and aggregates, they achieved a concrete that actually absorbed CO₂ during its manufacturing
• After analyzing their carbonated concrete, Rotta Loria and his colleagues found its strength rivaled the durability of regular concrete.
• based on our experiments, we show the strength might actually be even higher. We still need to test this further
• It could be used in beams, slabs, columns, foundations -- everything we currently use concrete for."
• "The findings of this research underline that although carbonation of cement-based materials is a well-known reaction, there is still room to further optimize the CO₂ uptake through better understanding of the mechanisms tied to materials processing,"

• Journal Reference:

   
   
  1. Xiaoxu Fu, Alexandre Guerini, Davide Zampini, Alessandro F. Rotta Loria. Storing CO2 while strengthening concrete by carbonating its cement in suspension. Communications Materials, 2024; 5 (1) DOI: 10.1038/s43246-024-00546-9

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• Researchers at Princeton and UCLA have developed a passive mechanism to cool buildings in the summer and warm them in the winter.

    

   
• coatings engineered from common materials can achieve energy savings and thermal comfort that goes beyond what traditional building envelopes can achieve
• "With the increase in global temperatures, maintaining habitable buildings has become a global challenge,"
• "In recent years there has been massive interest in cool roof coatings that reflect sunlight. But cooling walls and windows is a much more subtle and complex challenge."
• "By coating walls and windows with materials that only radiate or absorb heat in the atmospheric window, we can reduce broadband heat gain from the ground in the summer, and loss in the winter, while maintaining the cooling effect of the sky. We believe that this idea is unprecedented, and beyond what traditional roof and wall envelopes can achieve."
• The findings' impact is significant for two important reasons. First, the researchers show in the article that many common and low-cost building materials radiate heat in the narrowband and block broadband heat. Material such as polyvinyl fluoride, already used as siding material, could be adapted for the purpose, as could even more common plastics.
• "We were really excited when we found that materials like Polypropylene, which we sourced from household plastics, selectively radiate or absorb heat in the atmospheric window." Raman noted. "These materials border on the mundane, but the same scalability that makes them common also means that we could see them thermoregulating buildings in the near future."
• The second reason for optimism is that the potential energy impacts at the building scale are substantial. The researchers noted that seasonal energy savings with their mechanism are comparable to the benefits of painting dark roofs white. This could be useful as air conditioning cost and heat related casualties continue to soar worldwide. Mandal and Raman plan to continue this research further.
• "The mechanism we proposed is completely passive, which makes it a sustainable way to cool and heat buildings with the seasons and yield untapped energy savings."

• Journal Reference:

   
   
  1. Jyotirmoy Mandal, Jyothis Anand, Sagar Mandal, John Brewer, Arvind Ramachandran, Aaswath P. Raman. Radiative cooling and thermoregulation in the earth’s glow. Cell Reports Physical Science, 2024; 102065 DOI: 10.1016/j.xcrp.2024.102065

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• researchers have designed a new wearable fabric to help people beat the heat in urban settings. The material, reported in the journal Science, could find use in clothing, cooling facades for buildings and cars, and for food storage and transport.
• Existing cooling fabrics reflect sunlight and also wick away sweat to cool a person via evaporation. More recently, researchers have designed cooling fabrics that rely on the principle of radiative cooling: the natural phenomenon in which objects radiate heat through the atmosphere straight into outer space.
• But radiative cooling fabrics made so far are designed to work when laid horizontally as opposed to vertically, as they would be when worn.
• researchers at the University of Chicago made a new three-layer fabric. Its wool bottom layer wicks heat from the skin to the middle layer, which is made of silver nanowires that block heat from coming in. The top layer selectively emits heat into the atmosphere.
• In tests conducted in the urban heat island of Chicago and under blistering Arizona sun, the material stayed 2.3°C cooler than sports cooling fabrics and 8.9°C cooler than commercial silk used for summer clothing.

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