It has been an essential binder for the development of cities and communication routes, up to the present day with the new eco-sustainable concretes

It can be said that the cement binder, known as concrete, is It has truly been a revolution since ancient times, for the growth of peoples, improving the solidity and living comfort of homes, building more efficient and secure lines of communications and creating monuments that history has given us because they are solid and long-lasting.

From the Romans to the 21st Century

The history of concrete dates back many centuries, starting with the ancient civilizations of Egypt and of Mesopotamia, where it was used, albeit with a crude recipe, to create structures such as pyramids and temples.

However, the real diffusion of concrete, as a building material, occurred during the Roman Empire. Indeed, they developed a recipe that included the use of lime, sand, water and a form of pozzolana, a type of volcanic ash.

Opus caementicium was very versatile and was used to create structures such as bridges, aqueducts, basilicas, amphitheaters and even the impressive Colosseum. Its versatility and strength allowed it to bear heavy loads and resist the wear and tear of time.

To obtain the opus caementicium, a mixture was prepared using a mixture of lime (quicklime or hydrated lime) and sand. Subsequently, water was added to create a workable paste and the pozzolana, added as a binding material, gave the concrete greater strength and durability.

Another type of concrete used by the ancient Romans was the "opus reticulatum". This style of masonry consisted of an arrangement of small rectangular concrete blocks, usually placed in a lattice pattern.

Opus reticulatum was often used to coat the external surfaces of masonry structures, giving them a distinctive appearance.

In summary, the use of concrete during Roman times was an important contribution to architecture and engineering. The combination of lime, sand, water and pozzolan allowed the Romans to build long-lasting and resistant structures, leaving a legacy that can still be admired today in many Roman ruins.

After the fall of the Roman Empire, the use of concrete declined significantly in Western Europe during the medieval period. However, in other parts of the world, such as in Islamic architecture and Byzantine architecture, concrete continued to be used.

During the Industrial Revolution, this binder experienced a renaissance thanks to advances in cement manufacturing technology. In the 19th century, French engineer Joseph-Louis Lambot developed reinforced concrete, a combination of concrete and steel, which made it possible to build even stronger structures.

In 1848, Lambot created a small reinforced concrete boat which he presented at the Universal Exhibition in Paris. This invention was the first documented use of reinforced concrete.

Lambot incorporated an iron structure within the clay to increase its strength and durability, paving the way for a new way of building.

Lambot's idea did not immediately gain great recognition, but his work paved the way for further developments in the use of reinforced concrete.

Later, during the 20th century, engineers such as François Hennebique and Auguste Perret perfected and spread the use of reinforced concrete, contributing to its large-scale adoption in the construction industry.

Since then, concrete has become one of the most widely used building materials in the world, and widely employed for the construction of buildings, roads, dams, bridges and many other infrastructure.

In recent decades, new technologies have been developed to improve product performance, such as the use of additives to increase its strength and durability.

In summary, the history of concrete is a long and fascinating evolution, which has seen this material become one of the pillars of modern engineering and architecture.

What is recycled concrete

Recycled concrete is a type of binder obtained by recycling waste materials, coming from demolition or failure of existing concrete structures.

The concrete recycling process usually involves crushing the waste concrete portions into smaller pieces, which are then sorted into based on size and quality.

After selection, the concrete fragments are washed to remove any impurities and contaminants. At this point, the recycled material can be used as aggregate for the production of new concrete.

The use of recycled concrete offers several environmental and economic advantages. First, it allows you to reduce the amount of waste that ends up in landfills, thus contributing to environmental sustainability.

In addition, the use of recycled concrete requires less energy and resources than the production of a virgin one, reducing the overall environmental impact . Economically, recycled concrete can be a more cost-effective option than virgin concrete, helping to reduce construction costs.

However, it is important to keep in mind that recycled concrete might have some limitations in terms of strength and quality compared to virgin concrete. Therefore, proper quality control and evaluation of the specific characteristics of recycled concrete is required to ensure its suitability for use in specific projects.

What technical differences exist between recycled concrete and that with natural aggregates

Recycled concrete, compared to that made with natural aggregates, may present some technical and performance differences. Here are some of the most common:

Composition

Recycled concrete uses aggregates from waste materials from demolished concrete structures, while that with natural aggregates uses aggregates from natural materials, such as gravel and sand.

Quality of the aggregates

Recycled aggregates may contain impurities and residual contaminants, such as paints, coatings or reinforcing materials. These residues could affect the quality and strength of the recycled concrete. In concrete with natural aggregates, the aggregates tend to be quality controlled and free from contaminants.

Resistance

Due to possible impurities and the variability of recycled aggregates, recycled concrete may have a slightly lower strength than that with natural aggregates. However, with proper quality control and proper selection of recycled aggregates, it is possible to achieve strength levels similar to traditional concrete.

Durability

The durability of recycled concrete depends on the quality of the aggregates used and the characteristics of the recycled waste material.

Some studies suggest that recycled concrete could be less resistant to the action of aggressive agents such as corrosion of reinforcement or chemical attack than concrete with natural aggregates . However, corrective measures such as the use of admixtures or surface treatments can be taken to improve the durability of recycled concrete.

Sustainability

From an environmental point of view, recycled concrete offers a significant advantage over that with natural aggregates, in terms of reduction of demolition waste and of the overall environmental impact linked to the extraction of natural materials. Therefore, recycled concrete is often considered a more sustainable choice.

Where it is advisable to use recycled concrete

Recycled concrete can be used in different contexts and applications. Here are some examples:

Roads and pavements

Recycled concrete can be used for making roads, highways, sidewalks and other paving. In these contexts it can offer a cost-effective and sustainable solution, reducing the use of virgin materials and the overall amount of construction waste.

Civil engineering works

It can also be used in the construction of civil engineering works such as retaining walls, bridges, dams and drainage works. However, it is important to carefully evaluate the technical specifications required for the project and ensure that the recycled concrete meets the strength and durability requirements.

Prefabricated elements

It can also be used for the production of prefabricated elements such as concrete blocks, prefabricated floors, beams and pillars. Its use, in the production of prefabricated elements, can contribute to the reduction of production costs and the overall environmental impact.

Redevelopment and renovation works

Recycled concrete can be an appropriate choice during redevelopment or renovation projects, where waste materials from demolished structures are available. Using the recycled version can reduce the need to purchase virgin concrete and contribute to the sustainability of the project.

Which countries use recycled concrete the most

The use of recycled concrete originated in the 70s, when we began to experiment and adopt methods for recycling waste materials from the demolition of concrete structures.

However, large-scale adoption of recycled concrete came later, in the 1980s and 1990s, with the development of more advanced shredding techniques, selection and production of recycled concrete.

The use of recycled concrete has spread in various countries over the years. Some of the countries where the use of recycled products is particularly widespread are:

United States

The United States was among the pioneers in the use of recycled concrete. In the 1980s, product recycling was widely adopted in many US states, to address the construction waste problem and promote environmental sustainability.

European countries

Several European countries have adopted the use of recycled concrete significantly. For example, the Netherlands, Germany, the UK, France and Sweden have incorporated greening into their building practices and environmental regulations.

Japan

Japan has developed advanced techniques for concrete recycling and has made extensive use of the product in road and infrastructure construction, especially from 90's.

Australia

Australia has made significant progress in the use of recycled concrete, especially for road paving and infrastructure. Numerous initiatives and projects have been promoted to reduce the use of virgin materials and encourage the use of recycled ones.

Automatic translation. We apologize for any inaccuracies. Original article in Italian.