Introduction: From Prehistory to Modern Times

It is hard to imagine how the developed world would look without concrete. Even though this building material is commonplace in modern life, it has been used for thousands of years even before Egyptian pyramids and Roman structures.

This post takes a look at the history of concrete, how it came to be, and how it played a part in creating monumental buildings of the world.

Concrete stands as a testament to human ingenuity, evolving from ancient times to revolutionizing modern construction. Its roots trace back to ancient civilizations like Egypt and Rome, where early concrete forms were used to build enduring structures. However, it was in the 19th century that concrete, as we know it today, began to take shape.

History of Concrete Timeline: The Evolution

Etymology 

The word concrete comes from the Latin ‘concretus’, which means ‘grown together’ or ‘compounded’. 

The etymology of the word “concrete” traces its roots back to the Latin term ‘concretus,’ which translates to “compounded.” This linguistic origin embodies the essence of the material itself, denoting a substance formed by the amalgamation of various elements compounded together. The Latin ‘concretus’ derives from the verb ‘concernere,’ signifying “to merge.” This evolution captures the concept of cohesion and solidification, reflecting the nature of concrete as a composite material, composed of aggregates like gravel or sand bound together by a cementitious paste. 

Over time, this term has retained its essence, encapsulating the fundamental characteristic of unity and amalgamation evident in the structure and formation of concrete as we understand it today.

Prehistory: From prehistoric rubble mixes to Roman cement

Around 6500 BCE, desert reservoirs resembling concrete were constructed. These subterranean cisterns were designed by either the Nabataea or Bedouin merchants, who established a modest kingdom in the arid oases of southern Syria and northern Jordan. Some of these ancient cisterns can still be found in these regions today.

Around 5600 BCE, in the former country of Yugoslavia, specifically in the vicinity of Lepenski Vir along the Danube River, archaeological discoveries in the mid-1960s revealed dwellings featuring floors that bore a resemblance to concrete. These floors were likely composed of lime cement, likely sourced from a nearby deposit along the river, blended with sand, gravel, and water to mimic the mixtures reminiscent of modern-day concrete.

Around 3000 BC, the ancient Egyptians used mud and limestone to form bricks. In the history of concrete, limestone – or lime – plays a significant role as the base ingredient for cement, and has been used for centuries.

They also used gypsum and mortars in building the pyramids.

Difference between mortar and concrete

Concrete and mortar are both mixtures used in construction, but they differ in their compositions and purposes. Concrete consists of a blend of cement, water, aggregates (like sand, gravel, or crushed stone), and sometimes additives or admixtures. It’s a sturdy material used for building foundations, roads, and structural elements. On the other hand, mortar is a mixture of cement, water, and fine aggregates, mainly sand. It’s primarily employed to bind construction materials like bricks, stones, or tiles together, acting as a bonding agent in masonry work such as laying bricks or tiles.

One notable difference between concrete and mortar is their strength and application. Concrete tends to be stronger and more durable, suitable for load-bearing structures like foundations and roads due to its higher aggregate content. Mortar, with a higher proportion of cement to sand, is designed for bonding and holding materials together, commonly used in bricklaying or for smaller-scale construction where high strength isn’t the primary requirement.

Now back to the Egyptians, The Great Pyramid at Giza required about 500,000 tons of mortar, which was used as a bedding material for the casing stones that formed the visible surface of the finished pyramid. In this way, stone masons were able to carve and set casing stones with joints no wider than 1/50 of an inch.

Around the same period, the first deposits of cement compounds were formed. The northern Chinese used a form of cement in building the Great Wall.  Analysis using spectrometers has validated that a crucial element in the mortar employed for the Great Wall and other ancient Chinese edifices was glutenous, sticky rice. Some of these structures have withstood the test of time and have resisted even modern demolition efforts

Difference between cement and concrete

Concrete vs. Cement

Concrete and cement are often discussed in relation to each other but they are not the same material.  Cement is the key ingredient in concrete. It is a fine powder, typically made of clay, limestone, and other minerals, serving as the binding agent when mixed with water and aggregates like sand and gravel. So, concrete is the final composite material formed by combining cement with these aggregates and water.

Concrete Ingredients

• Cement
• Combinations of limestone, clay, silica sand, chalk, shells, chalk, shale, slate, blast furnace slag, and iron ore

Concrete Mixture Process

• Add water to the cement 
• Mix with sand, gravel, or crushed stone
• Crush all the ingredients together
• Heat them at a high temperature
• Ground them into powder.

Concrete consists of a blend of the cement-water mixture. This mixture envelops the sand and rocks, uniting them to create what we recognize as concrete. When in its fluid state, concrete can be molded into various forms desired by the constructor. Upon the evaporation of water from the mixture, the concrete solidifies into a rigid structure, preserving the chosen shape.

Cement generally makes up about 10 to 15% of the concrete mix.

Greece and Rome

By 600 BC, the Greeks discovered a chemical reaction that changed the ways concrete could be used. By mixing a natural pozzolan(volcanic sand)found on Santorini Island with lime, they created concrete that would harden well. The pozzolan contains silica-alumina that develops hydraulic properties when mixed with lime. They used the pozzolan to create protective coverings for structures.

However, this blend lacked the necessary strength for substantial construction purposes.

By 200 BC, the Romans were building their structures very successfully using concrete. They discovered a similar chemical reaction to the Greeks when they mixed volcanic ash with lime. A further benefit of this improved concrete was that it could also hold up when submerged in water, something previously not possible with plaster made of lime and sand.

Colosseum & Pantheon

Between 70 CE and 80 CE, the Colosseum was erected in Rome. This magnificent structure was situated on an artificial lake that had been a part of Emperor Nero’s palace during his reign from 54 to 68 CE. The initiative for its construction stemmed from Emperor Vespasian (ruling from 69 to 79 CE), who envisioned creating the world’s largest theater. Originally designated as the Flavian Amphitheater, its name evolved into the Colosseum during the Middle Ages.

With a capacity exceeding 50,000 seats and boasting 76 archway entrances corresponding to these seats, the Colosseum stood as a testament to grandeur. Remarkably, approximately a third of this architectural marvel remains intact, still awe-inspiring to visitors today.

Between 118 CE and 128 CE, the Pantheon was constructed utilizing unreinforced concrete, marking an architectural marvel of ancient Rome. As it nears its 1,900th anniversary, the Pantheon remains remarkably robust. The temple’s defining feature, its unreinforced concrete dome, stood unparalleled in its time, boasting dimensions twice the width and height of any other dome built then. This vast dome, spanning 143 feet, centered around the renowned “oculus.”

Supporting its immense weight, the structure relied on thick concrete walls and eight barrel vaults, all fortified with brickwork. Remarkably, these elements provided the necessary buttressing without requiring internal support, highlighting the ingenious engineering of the Pantheon.

Today’s constructors and engineers wouldn’t dare build a dome of that size with unreinforced concrete, and they may never know the secret to the Pantheon’s enduring stability. 

Read also: A deep dive into masonry and composite materials

Concrete in Modern Times: Advancements in Concrete Technology

In the 20th century, advancements in construction materials notably enhanced the capabilities of concrete. One significant innovation involved reinforcing concrete with steel bars, known as reinforced concrete. This fortified version surpassed plain concrete in strength, finding use in demanding construction like buildings and bridges. Steel bars, or rebar, embedded within the concrete before it sets, bolster its support and tensile strength.

Another breakthrough came with precast and prestressed concrete components—beams, columns, walls, and expansive structures like bridges—crafted offsite and then transported for assembly. Prestressed concrete, involving tensioned cables within the concrete before it sets, amplifies its support and tensile strength, expediting construction and potentially reducing expenses.

To cater to contemporary construction demands, new concrete variants emerged. For instance, self-consolidating concrete offers high fluidity and easy placement sans vibration, while high-performance concrete boasts superior strength and durability. These adaptations prove invaluable in scenarios where traditional concrete falls short, such as in high-rise buildings or areas facing extreme weather conditions.

Modern Era and Modern Concrete: Taking a Quick Look Back

1824: Revolutionizing Cement Production

Joseph Aspdin, an English bricklayer, introduced Portland Cement, revolutionizing modern concrete by heating a chalk and clay mixture to create a fine powder. His innovation laid the foundation for contemporary concrete 

Mid-19th Century: Refinement of Cement Production

Joseph’s son, William Aspdin, enhanced cement production, creating superior calcium silicates, advancing cement strength significantly 

1828: Mass Production Sparks Adoption

Mass production commenced in 1828, leading to the widespread adoption of this game-changing cement and initiating the concrete revolution 

1849: Invention of Iron-Reinforced Concrete by Joseph Monier

Joseph Monier, a French gardener, successfully experimented with pouring concrete over steel mesh(due to their similar expansion rates, concrete and steel make an excellent combination), creating iron-reinforced concrete, enhancing tensile strength and durability 

1880s: Patenting of Prestressing Steel

Prestressing steel, a patented method for reinforcing concrete, minimizes material usage while increasing strength. By applying stress to the concrete before it encounters loads, high-strength steel tendons are embedded within the material before it sets, enhancing its structural integrity. By preloading the concrete with this stress, it counteracts the expected forces the structure will endure, effectively enhancing its ability to withstand those loads once in use

1886: Introduction of the First Rotary Kiln

The first rotary kiln replaced less economical vertical shaft kilns, improving concrete manufacturing quality and economy

1889: Ernest Ransome’s Reinforced Concrete Patent

Engineer Ernest Ransome patented reinforced concrete, leading to the construction of the oldest surviving reinforced concrete bridge, the Alvord Lake Bridge 

1891: First Concrete Street in America

George Bartholomew built the first concrete street in Bellefontaine, Ohio, advocating for its environmental friendliness

1903: First Concrete High-Rise

Ransome’s system enabled the construction of the first concrete high-rise, the 16-story Ingalls Building in Cincinnati 

1913: Introduction of Ready-Mix Concrete

The debut of ready-mix concrete from a centralized plant in Baltimore City revolutionized construction. This pre-made blend of cement, aggregates, and water transformed job sites by offering precise, quality-controlled mixes delivered directly. It replaced on-site mixing, ensuring accuracy, reducing errors, and boosting efficiency. This innovation standardized concrete use, speeding up projects and enhancing construction quality.

1915: Introduction of Colored Concrete

L.M. Scofield, a significant company in the concrete industry, produced color for concrete, diversifying its usage in construction projects 

1931: Construction of the Hoover Dam

The Hoover Dam marked a milestone as the largest-scale concrete project at that time, using over four million cubic yards of concrete in construction 

1939: First 3D Printed Concrete Structure

William E. Ursche, an American inventor and entrepreneur, created the first 3D-printed building from concrete in Indiana, employing layered, horizontal slip forming for construction

1963: First Concrete Sports Dome

The University of Illinois witnessed the construction of Assembly Hall, the first sports arena with a concrete dome

1970s: Introduction of Fiber Reinforcement

Fiber reinforcement strengthened concrete, finding applications in various structures and outdoor features

1992: Tallest Reinforced Concrete Building

The skyscraper at 311 South Wacker Drive in Chicago was the world’s tallest reinforced concrete building at that time

1998: Introduction of Silica Fume for High-Strength Concrete

Silica fume usage led to very high-strength concrete construction in buildings like Two Union Square and the Pacific First Center 

1998: Invention of Green Concrete

 Dr. WG of Denmark invented green concrete, incorporating eco-friendly materials and enhancing resistance to damage

2006: Introduction of Self-Healing Concrete

Self-healing concrete, capable of repairing cracks, was developed using bacterial stimulants secreting limestone

2022: Advancements in 3D Printing

Modern 3D printing combines concrete with wood framing, creating affordable, minimal-waste residential construction.

Read also: What is Blockwork Covered in Concrete?

The Future of Concrete

Despite centuries of research, until now, no one has yet found out how the ancients made concrete. However, researchers plan to use similar volcanic ash from the Californian coast to see if they can reproduce Roman-style concrete.

If this happens, the combination of Rome’s secret concrete recipe and modern rebar engineering techniques might revolutionize the world’s infrastructure and architecture — all over again.

In the not-so-distant future, concrete is set to undergo a revolutionary transformation, embracing sustainability and innovation on a remarkable scale. Engineers and scientists are pioneering the development of “green” concrete, utilizing recycled materials, such as industrial byproducts and even waste, to reduce its environmental footprint. Moreover, the integration of advanced technologies like self-healing concrete, and self-cleaning concrete, promises extended durability and decreased maintenance needs. 

With a focus on enhancing strength, flexibility, and eco-friendliness, the future of concrete holds incredible potential, reshaping infrastructure while aligning with the urgent global drive toward sustainable construction materials.

Traditional vs. Modern Construction Techniques 

Traditional Construction

Emphasizes conventional methods using bricks, timber, and mortar. It typically requires more labor, and time, and might have limitations in design flexibility 

Modern Construction

Integrates innovative methods like prefabrication, modular construction, and advanced materials such as reinforced concrete. These techniques reduce construction time, labor costs, and offer enhanced structural strength and design possibilities 

The evolution of concrete showcases the transformative power of innovation in construction, from ancient wonders to the skyscrapers of today. As modern construction methods continue to evolve, concrete remains a cornerstone in building resilient and awe-inspiring structures that shape our world.

Conclusion

Concrete, a cornerstone of modern civilization, embodies centuries of human ingenuity. From its humble beginnings in ancient Egypt and Rome to its pivotal role in shaping contemporary cities and structures, this remarkable material reflects the world’s relentless pursuit of progress and innovation.