Internal strength

I grew up in New Zealand where most homes are made of wood or brick. So it was a shock to come to Israel and find that most homes here are built with poured concrete. I am reminded of this now particularly as they are constructing a new building next to my office.

The Romans knew how to build using concrete. Many of their buildings and structures are still standing two millennia later. Caesarea harbor is an example of the use of concrete in a large-scale underwater project. The Pantheon and Colosseum are incredible concrete structures. The “secret ingredient” that turned cement into concrete was volcanic ash. But sometime after the sixth century, when Justinian built the Hagia Sophia in Turkey, people stopped building with concrete. And the secret was largely forgotten.

It was not until early in the 18th century that people rediscovered the properties of concrete that make it an ideal building medium. John Smeaton rebuilt the Eddystone Lighthouse off the Cornwall coast in 1759, using concrete with hydraulic lime, pebbles and powdered brick.

But the problem with concrete is that although it is very strong in compression, it is weak in tension. This means that a concrete floor supported only at the edges will crack and fall when heavy loads are placed on it. And if an earthquake hits, it will fall very quickly.

Rebar for foundations and walls of a sewage pump station. (CC BY, Argyriou / Wikimedia Commons)

For this reason, nowadays we build with reinforced concrete. Metal rods, wires or mesh are embedded within the concrete to give it tensile strength. The metal inside the concrete is known as rebar (an abbreviation of “reinforcing bars”), and this supports so much of the infrastructure you see around you, including bridges, highways, buildings, foundations and dams.

Modern reinforced concrete was invented by a couple of Frenchman independently of each other.

A gardener in the Louvre Gardens named Joseph Monier was looking for ways to build stronger flower boxes for his displays. In 1846, he hit upon the idea of using steel to reinforce the cement.

At about the same time, Joseph Louis Lambot started making crates and shelves from wire covered in cement. In 1848 he built a reinforced concrete boat, which was later displayed at the 1855 Paris Exposition.

Joseph Lambot’s reinforced concrete boat at the Brignoles museum. (CC BY-SA, Jorune / WIkimedia Commons)

A concrete boat may sound like the punchline of a joke, but in fact concrete boats were built and used throughout the 20th century. Although they were heavier and slower than wooden or steel-hulled boats, the construction materials are cheap and readily available. During the late 19th century many European rivers had concrete barges floating along them, and during both World War I and World War II, due to steel shortages, the US military constructed fleets of ocean-going concrete ships. Since the 1970s, US universities have competed in the concrete canoe competition, which in 2024 was won by the University of Florida.

In his patent, Lambot wrote,

My invention is a new material to replace wood in shipbuilding and anywhere else where it is exposed to moisture, such as wooden floors, water tanks and plant containers. This new substitute material consists of a metal lattice made up of bars and braces tied together or assembled into a basket of a specific shape. I give this lattice the shape most suited to the object I want to produce and then drown it in hydraulic cement, which also solves the problem of possible joints.

However, it was an Englishman, Ernest Ransome, who began using reinforced concrete for widespread construction. Back in Ipswich, Ransome had worked in his father’s artificial stone factory. In the 1870s, he moved to California and began experimenting with better ways to bond reinforced steel to concrete.

According to Roman Mars, in his 99 Percent Invisible podcast, Ransome thought of twisting the steel after he found a twisted rubber band in his pocket one day and thought, “Well, that’s what I’m going to do to this iron bar. I’m going to twist it so it just binds to the concrete better.”

According to Ransome’s patent:

In my invention the rods or strips B are twisted, and by their spiral shape they form a bond or tie at all points from end to end Within the material through which they pass.

With his patented reinforced concrete, Ransome built, in 1888, the Bourn Winery, the Torpedo Building (in 1890), the Alvord Lake Bridge and the Conservatory Bridge in Golden Gate Park (both in 1890) and the 1891 Art Museum, now being used as the Canter Center on the Stanford University campus. Soon after that, Ransome moved with his wife, Mary Jane Dawson Ransome and their eight children, to New York and later New Jersey. He felt his buildings were under appreciated on the West Coast. The true test of his construction methods came in 1902, when the Pacific Coast Borax Refinery that Ransome had built in 1897, caught fire, destroying everything within. The concrete frame suffered only very minor damage. But the real proof of his idea came after his buildings were among the few to withstand the 1906 San Francisco earthquake.

Kavanagh Building in Retiro, Buenos Aires, Argentina, made of reinforced concrete. (Public Domain/ Wikimedia Commons)

Today there are other forms of rebar reinforcing our concrete. But the principles pioneered by Monier, Lambot and Ransome are still fundamentally what supports our infrastructure.

There are two things in common to all reinforced concrete. The rebar has to be entirely encased in a thick layer of concrete. If it is exposed to the elements, the rebar will rust, causing it to expand and press on the concrete until it cracks, while the rusted metal can no longer provide structural support. Similarly, even the best made reinforced concrete does not last forever. Unlike the Roman concrete construction which has lasted for millennia, bridges, roads and buildings made with reinforced concrete must be well maintained and replaced every fifty years or so.

The great strength of rebar is that it invisibly holds everything together. Its weakness is that when we ignore it, things collapse. For example, one of the likely causes of Florida’s 2021 Surfside condominium collapse was that saltwater had worn away the concrete, exposing the rebar inside, which meant the building was no longer structurally sound. Failing to maintain the infrastructure led to the collapse of a 12-storey building and the deaths of 98 people.

This may be heretical, but I want to compare Isaac’s role in the formation of the Jewish nation to that of rebar. Throughout his life he was almost always passive. The Torah tells no heroic adventures about Isaac. He was overshadowed by the stories of his father Abraham, his wife Rebecca and especially his children Jacob and Esau.

Isaac did not gather followers like his father; he rarely left his home and almost never confronted the difficulties of the world, like Jacob and Esau. And, as we read in this week’s Torah portion of Toledot, the most famous story about Isaac is how he was duped by his wife and son to giving his blessing to the wrong son. There were only a few episodes when he was active.  When there was a drought and he went to the land of the Philistines. Even then, God told him he could not go to Egypt, which had been his plan. While living in Gerar under the protection of Abimelech, king of the Philistines, he used the same ruse as his father, claiming his wife was his sister. When he left Gerar he went and dug the same wells his father had dug earlier (Genesis 26).

Like rebar, which must be fully encased in concrete, Isaac is most famous for being bound on the altar by his father. In our prayers, we often ask God to remember the binding of Isaac.

But it would be a huge mistake to think that Isaac made no contribution to the nation. He is one of the patriarchs precisely because he provided the stability that allowed for continuity. Without his inner strength, there would have been no future for Abraham’s descendants.

According to tradition, Isaac represents the attribute of gevurah — strength. The mishna in Avot (4:1) explains:

Who is mighty? One who conquers his inclinations

The binding of Isaac, his complete self containment, gave him the strength to reinforce the nation that came after him.

Isaac also represents din — justice. Abraham represents chesed — outgoing kindness. Jacob is tiferet, outward-facing beauty and splendor. But Isaac’s justice is the backbone of it all. Without a strong system of law and justice, cracks appear and everything falls apart.

Like reinforced concrete, law and justice are things that we take for granted. It is only when things go wrong that we start to pay attention to the potential collapse of the legal system.

One of the reasons posited for the downfall of the Roman Empire was the corruption and instability of the government. Without the internal strength of justice the empire was unable to withstand the military, economic and health challenges it faced.

Isaac is the paradigm of strength. He does not build upward or outward on what came before, but spent his time with the equally important function of ensuring that the foundations of the structure were solid.

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