Korva rescues the ideas worth keeping from podcasts. Each one becomes a Card.

Built to Last

Theo Alden@theoalden

15 cards

From Medieval WisdomWhy Roman CONCRETE Lasts 2000 Years While Ours Dies in 50

Roman concrete at Caesarea has survived submerged in salt water for about 2,000 years, while modern versions often fail within decades.

From Medieval WisdomWhy Roman CONCRETE Lasts 2000 Years While Ours Dies in 50

In an MIT test, modern concrete cracks stayed open while Roman hot-mixed concrete cracks completely healed within two weeks under running water.

From Medieval WisdomWhy Roman CONCRETE Lasts 2000 Years While Ours Dies in 50

The Pantheon’s massive 142-foot dome contains no steel rebar and has endured for nearly two millennia.

From Medieval WisdomWhy Roman CONCRETE Lasts 2000 Years While Ours Dies in 50

Roman concrete heals cracks when water dissolves reactive lime clasts, carries calcium-rich solution inside, and recrystallizes it into reinforcing minerals.

From Medieval WisdomWhy Roman CONCRETE Lasts 2000 Years While Ours Dies in 50

Modern concrete hardens in 28 days for speed. Slower Roman curing created a more stable material with fewer internal stresses and microcracks.

From Medieval WisdomWhy Roman CONCRETE Lasts 2000 Years While Ours Dies in 50

Steel added to strengthen concrete can become the mechanism that destroys it when corrosion protection fails.

From Real EngineeringWhy Sagrada Familia Took 144 Years to Complete

In June 2026, Sagrada Família’s Jesus Christ tower reached 172 meters, becoming the world’s tallest church after 144 years of construction.

From Real EngineeringWhy Sagrada Familia Took 144 Years to Complete

Spanish Civil War destruction of Gaudí’s plaster molds turned the Sagrada Família into a reverse-engineering project.

From Real EngineeringWhy Sagrada Familia Took 144 Years to Complete

The Sagrada Família’s reconstructed designs were generated with software first created for fighter-jet wing surfaces.

From Real EngineeringWhy Sagrada Familia Took 144 Years to Complete

A hanging string rests entirely in tension, revealing the compression path a stone structure needs.

From Practical EngineeringThe Mind-Blowing Flaw That Flooded New Orleans

New Orleans’s Katrina catastrophe was not simply a natural disaster. Critical flood defenses failed below their designed protection level.

From Practical EngineeringThe Mind-Blowing Flaw That Flooded New Orleans

The 17th Street Canal levee failed when foundation soil sheared along a weak plane beneath unexpectedly low water.

From Practical EngineeringThe Mind-Blowing Flaw That Flooded New Orleans

New Orleans’s levee system turns the city into a bowl: it keeps floodwater out but traps rainwater inside, requiring pumps.

From Wendover ProductionsWhy American Houses Are So Flimsy

The average American has more than twice the living space of the average Brit, about 800 square feet versus 390.

From Wendover ProductionsWhy American Houses Are So Flimsy

US asphalt-shingle roofs install faster and cost less, but last 15–30 years versus about 50 for English tile.

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Save Cards from different podcasts around one subject, then return to the ideas that matter.