The Secret of Roman Concrete

Roman concrete was durable and self-repairing, and quite a bit of it is still around, whereas modern concrete’s lifespan can be measured in decades. The assumption had been that this because of a key ingredient: pozzolanic ash. But a study published yesterday in Science Advances suggests that the Roman process hot mixed quicklime, leaving lime clasts in the matrix that, by dissolving when exposed to water and then re-forming, could fill cracks in the concrete. More at MIT News.

The Sixth

Today marks the 88th anniversary of le 6 février: on 6 February 1934, far-right paramilitary leagues rioted in Paris in an attempt to overthrow the newly installed French government. Does that sound familiar? John Ganz thought so too. “So, just how similar were Feb 6 1934 and Jan 6 2021? Starting somewhat superficially, it has to be admitted that there is an eerie parallelism: both involve a far-right mob with many military veterans attempting to to storm the legislative branch that was in the process of recognizing a new administration.”