zlacker

"This means that concrete structures, for all their stone-like superficial qualities, are actually made of the skeletons of sea creatures ground up with rock. It takes millions upon millions of years for these sea creatures to live, die and form into limestone. This timescale contrasts starkly with the life spans of contemporary buildings."

This description is fairly accurate. The CaCO3 (used as a source of calcium in the cement component of concrete) is completely decarbonated in a 1450°C kiln in the process of cement manufacture, combined with silica (from shale) +/- SO4 (from gypsum) and sintered to form an anhydrous calcium silicate (clinker: e.g. tricalcium silicate, Ca3SiO5, ‘alite’), then powdered (e.g. ordinary Portland cement, OPC). The skeletal limestone is long gone — and the above decarbonation step is the reason cement manufacturing process is a significant GHG source (in addition to fuel consumption by the kiln itself).

Mixing water with the powdered clinker generates a very rapid, exothermic, partial dissolution of the primary silicate. The rapid release of silica results in nucleation and growth of calcium silicate hydrate (CSH) plus Ca(OH)2. CSH binds the remaining unreacted solid mass together, giving cement its durability and strength.

>>rsa404+(OP)
Sorry, typo: fairly inaccurate

>>rsa404+(OP)
Yeah that section seemed like creative writing and stretching for a metaphor. Kind of detracted from the overall point about rusting infrastructure.