Ode to concrete - Roman Style :)

Concrete, modern style, craps out within 30-50 years, depending on the weather, while concrete, Roman style, lasts millennia, even when submerged, thanks to a secret sauce just beginning to be understood thanks to esoteric tech of the sophisticated kind.

He (Pliny the elder) might be pleased, then, to see an ancient technology that he himself admired taking on a modern relevance and novelty. Who, Pliny wondered, could help but be surprised at the way the Roman harbor infrastructure, made from a mix of lime and volcanic ash, overcomes entropy, “forming a barrier against the waves of the sea, becoming changed into stone the moment of its immersion, and increasing in hardness from day to day—more particularly when mixed with the cement of Cumae,” an ancient city in Naples?

The geologist and geophysicist Marie Jackson, of the University of Utah in Salt Lake City, shares Pliny’s admiration for these still-standing structures, and has scoured ancient Roman texts in hopes of uncovering the recipe that makes them so durable. The goal would be to revive Roman concrete, and their building techniques, for the modern age—but, alas, her efforts were to no avail.

So she’s been working backwards. In “Unlocking the secrets of Al-tobermorite in Roman seawater concrete,” a study she and her colleagues published in 2013, they confirmed, via trace element analyses at the Advanced Light Source, an X-ray synchrotron at the Lawrence Berkeley National Laboratory in California, that drill cores of a 2000-year-old block submerged in the Bay of Pozzuoli near Naples came “from Flegrean Fields volcanic district, as described in ancient Roman texts.” The samples contained aluminum tobermorite, a rare mineral and not an ingredient in conventional concrete, which accounted for their great durability and strength. In another study published this month, the researchers found that the aluminum tobermorite grew out of a silicate mineral common to volcanic ash, called phillipsite, spurred by ocean contact. “We’re looking at a system that thrives in open chemical exchange with seawater,” Jackson said.

The tobermorite’s long plate-like crystals grant the concrete an unusual flexibility under stress that increases with time submerged. “It’s a very rare occurrence in nature,” Jackson said. By contrast, modern concrete, made from a mix of Portland cement and coarse aggregate, corrodes in seawater within decades, making the application of Roman concrete, Jackson noted, an enticing option for steel reinforcement-free seawalls that guard against rising sea levels.

Pliny the Elder would be pleased.