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Cake day: June 12th, 2023

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  • Reinforced autoclaved aerated concrete (RAAC) is a lightweight material that was used mostly in flat roofing, but also in floors and walls, between the 1950s and 1990s.

    It is a cheaper alternative to standard concrete, is quicker to produce and easier to install.

    It is aerated, or “bubbly”, like an Aero chocolate bar.

    But it is less durable and has a lifespan of around 30 years.

    Its structural behaviour differs significantly from traditional reinforced concrete.

    Moreover, it is susceptible to structural failure when exposed to moisture. The bubbles can allow water to enter the material.

    If that happens, any rebar reinforcing RAAC can also decay, rust and weaken.

    Because of this, RAAC is often coated with another material, such as bitumen on roofing panels. But this material can also degrade. Source

    This is an international issue btw.











  • Because of their ubiquitous usage and environmental persistence, humans are exposed to a variety of PFAS, primarily through ingestion of contaminated water and food, though PFAS have also been detected in air, indoor dust, and consumer products (Domingo and Nadal, 2017; Sunderland et al., 2019).

    While certain communities can be highly exposed to PFAS due to proximity to an industrial site or occupational exposure, PFAS exposure is ubiquitous among human populations, with 98 % of the U.S. population having detectable concentrations of PFAS in their blood (Calafat et al., 2007; National Center for Environmental Health Agency for Toxic Substances and Disease Registry, 2023).