Retaining walls have played a surprising role in shaping civilization. They’ve offered essential support in agriculture, construction, and infrastructure. Thousands of years ago, stone and clay bricks protected early cities from flooding and provided a base for buildings. Today, precast retaining walls are made in factories and then transported ready-made to construction sites.

Ancient civilizations

Retaining walls were important to the development of terraced farming and the construction of cities. Early examples include the Sumerians in Mesopotamia (modern-day Iraq). During the third millennium BCE, the city of Ur was the capital of the Sumerian civilization and known for its impressive architecture. The city used retaining walls of stone and clay bricks to create raised platforms, protecting Ur from seasonal flooding and supporting their buildings.

In ancient Egypt, retaining walls were used for terraced landscapes for agriculture along the Nile River. These walls prevented soil erosion and improved irrigation, allowing the Egyptians to cultivate crops in tricky conditions.

The Inca civilization in South America used retaining walls to support terraced fields on steep mountainsides. Machu Picchu, the 15th-century Inca citadel, used huge stone terraces surrounding the site to prevent landslides and soil erosion. The long-term stability of the structures was secured, and the site is a popular tourist attraction today.

The ancient Greeks and Romans also used retaining walls, especially in hilly regions. The Romans developed more advanced techniques for constructing retaining walls, incorporating mortar and ashlar masonry for better strength and durability. These walls were important for the aqueducts and roads that supported the Roman Empire.

These early walls lay the groundwork for today’s precast retaining walls. Precast walls are used in a variety of road, railway, and urban development projects. Companies like Modular Cubed allow for quicker installation and reduce construction costs by up to 70%.

The Middle Ages and the Renaissance

During the Middle Ages, retaining walls were used for military and agricultural purposes. Castles were often built on elevated ground and required strong walls to support their structures. Builders relied heavily on stone. In the Renaissance era, engineering advancements and more sophisticated architecture led to more refined designs. Leonardo da Vinci and his contemporaries studied earth pressure, eventually leading to our modern understanding of geotechnical engineering. Architects and engineers started to incorporate principles of load distribution and pressure management, allowing for longer lasting walls.

Industrial Revolution

The 18th and 19th centuries brought significant changes to construction, primarily through new materials and technologies. Reinforced concrete provided stronger and more versatile material. Concrete could now be moulded into various shapes and allowed for more complex retaining walls. The introduction of steel reinforcements helped allow for stronger walls to support larger structures. Railway and road construction necessitated the use of retaining walls to stabilise embankments and prevent landslides. The mass production of steel meant these walls were more cost-effective, allowing for more walls in both urban and rural settings.

Today’s Precast Retaining Walls

Precast retaining walls became popular in the mid-20th century. Unlike traditional poured-in-place concrete, these walls are made away from the construction site and can be manufactured more precisely. This has led to their widespread use in projects that require uniformity and durability. Precast walls include gravity walls, which hold back soil, cantilever walls which use reinforced concrete, and counterfort walls with additional vertical supports (counterforts). Due to their off-site manufacturing, precast retaining walls are more environmentally friendly. Construction waste is minimised, and less energy is required.