The construction world is constantly evolving and changing. We are always searching for new and innovative ways to construct structures that are efficient, sustainable, and durable. In this blog post, we will explore the return to ancient building methods and give some examples of new methods being developed using old ideas.

Self-Healing Ancient Roman Concrete

When we talk about how durable concrete is, we always mention ancient Roman concrete structures. But the truth is, modern concrete struggles to get even close to the same durability as the ancient type. So, researchers have been looking into what made roman concrete so strong.

The prevailing thought has been that roman concrete was so durable because it was made from a unique blend of volcanic ash from mount Vesuvius near Naples. This volcanic ash had qualities that allowed it to harden even when it was exposed to moisture.

But, new studies are revealing that what we previously thought was a mistake, may have been the biggest reason for roman concrete’s durability.

Ancient roman concrete contains white chunks, known as “lime clasts.” These white chunks were a key part of the concrete and most thought they were just a result of low quality control.

Now researchers with the Massachusetts Institute of Technology, using high-resolution multiscale imaging and chemical mapping techniques, have determined that the lime used was quicklime. Quicklime is more reactive and adding this to concrete results in something called hot mixing.

“The benefits of hot mixing are twofold,” MIT professor of civil and environmental engineering Admir Masic told Science Daily. “First, when the overall concrete is heated to high temperatures, it allows chemistries that are not possible if you only used slaked lime, producing high-temperature-associated compounds that would not otherwise form. Second, this increased temperature significantly reduces curing and setting times since all the reactions are accelerated, allowing for much faster construction.”

The researchers also realized that this makes the concrete self-healing. Cracks in the concrete would start to form in the lime clasts too. As water flows into the cracks, it reacts with the quicklime. The reaction fills up the crack with the resulting calcium carbonate.

The research team hopes to develop this information into a method that creates concrete that lasts as long as the ancient roman structures.

Returning to Ancient Building Practices for the Environment’s Sake

One big reason builders and engineers are starting to look to the past for inspiration is the increased focus on sustainability.

Ancient building practices were more environmentally friendly than modern practices due to their reliance on natural materials, such as bricks of clay, timber, or stone. Buildings were often integrated into or constructed with the surrounding environment in consideration.

The Xi’an University of Architecture and Technology has been developing a new cement-stabilized rammed earth technique.

Rammed earth construction is an ancient building technique that has been used for centuries, traditionally in cases where access to other materials may have been limited. The technique involves mixing soil and gravel together, then filling timber frames with the mixture and compressing it down in layers.

Traditional rammed earth also relied on a natural stabilizer, like plant matter or animal urine. The new cement-stabilized rammed earth technique incorporates cement into the mixture to act as a stronger stabilizer.

Ancient building practices also incorporated sustainability in the construction process itself. For instance, they often employed locally-sourced materials, and reduced the amount of waste generated during the construction.

In recent years, the University of Plymouth has been developing a new, sustainable building material called CobBauge. Remixing the ancient method of cob building to create a new and more efficient building material – that relies heavily on a waste material.