Concrete Architecture: why should it be preserved

Concrete as Architecture: Concrete may be the most controversial and criticized construction material ever. Buildings made of concrete are often reviled as ugly and thus not worthy of consideration as cultural heritage.

Significant concrete buildings are threatened by a general lack of understanding, appreciation and recognition of their full range of cultural values. Because they are all too often undervalued, they are subject to redevelopment pressure, unsympathetic change or neglect.

Why does concrete need to be preserved?

For many, concrete is merely a composite material made of water, sand and stone aggregates. In fact, it is important for people to understand that concrete, as a construction material, has changed the way architects and engineers have designed buildings and shaped our built environment.

Although a form of concrete was already employed during the Roman Empire, the procedure to produce Portland cement and reinforced concrete was not patented until the 19th Century, promoting a revolution in design opportunities and construction techniques and giving rise to Modern architecture in the first years of the 20th Century. The new concrete structures were often designed to present a fair-faced condition celebrating the natural characteristics of the material and express the way it was formed. Concrete as architecture was at the center of the architectural currents during the 20th Century and continues on today.

Unité-d’Habitation-in-Marseilles, France - Photo by André P. Meyer-Vitali on Flickr

The common use of natural exposed fair-faced concrete in the 20^th century over time can experience deterioration, especially when subjected to an aggressive environment. Damage produced in concrete can be divided into 3 basic groups:

• Physical effects: Frost actions and temperature variations can cause cracks;
• Chemical effects: like chloride aggression and leaching, common in structure near the sea;
• Biological effects: the appearance of stains is a result of the proliferation of microorganism and stress from invasive tree roots that can cause cracks.

The early manifestation of most of these deterioration processes is the onset of nano- and micro-cracks, increasing their width with progressive untreated decay, followed by erosion and material losses. In addition, lowered pH due to carbonation, acidic solutions or the presence of chlorides cause depassivation of the reinforcing steel causing corrosion in the form of rust. The expansive pressure caused by this corrosion only increases the stresses on the surrounding concrete thus accelerates cracking and the whole deterioration process. In the case of biological decay and black crust formation (sulphate and chloride corrosion), stains can also be visible in the concrete surface creating a negative aesthetic effect.

The angel - Commemorative monument | Torricella Peligna (Italy - 1922)

Currently, the most common strategies employed to delay concrete degradation are related to modifications carried out during its fabrication process:

• by decreasing the porosity;
• by reducing the water to cement ratio;
• by adding nanoparticles or other nanostructures as a reinforcement.

In the case of concrete structures built in the 20th Century, no particular care was given to critical parameters increasing their long performance, such as the water to cement ratio and the thickness of the concrete layer, because decay mechanisms were largely unknown and poorly understood at that time.

Thus, historic unmaintained concrete often is viewed as having low durability putting the historically significant structures in danger. In recent years, many concrete masterpieces have been demolished or have been inappropriately altered, sometimes beyond recognition, due to a lack of appreciation for their cultural value and lack of understanding and knowledge of the opportunities for proper maintenance and repair.

For this reason, one of the InnovaConcrete project objectives is to promote Awareness about the relevance of the 20th Century Cultural Heritage.

A preliminary analysis of citizen awareness about tangible 20th Century Cultural Heritage clearly reveals that buildings and sites built during the first half of the 20th Century (1890-1945) under the Modern Movement, currently enjoy a certain degree of recognition.

However, newer buildings, particularly those with concrete as a primary finish material, suffer neglect and on-going decay. Some iconic buildings are alarmingly under threat of demolition. A representative example of such buildings is the east-European architecture from the socialism period (read more about Architecture in Socialism Period). These buildings are often in urban environments and include bridges, residential and commercial buildings and train stations. For this reason, they are too often treated as insignificant public use structures and not recognized as important Cultural Heritage

Memory Park (Kiev) | 1968–1981 | Photo by Socialist Modernism

One example is the Warsaw Train station, by Architect Arseniusz Romanowicz, which is a typical example of a reinforced concrete thin-shell structure, one of the important achievements of the post-war modern movement, being a clear symbol of socialism architecture.

Warsaw Train Station (Poland) | 1962-1963

It is very important to preserve these monuments, searching for the best practices to respect their architectural character as they represents specific cultural movements and ideals of important 20th century architects.

In general, the conservation of historic buildings and monuments generates a high level of activity within the global economy and the associated employment. The investment in repair and conservation in the construction sector produces even more employment than that generated by new construction. The total annual global spending on cultural conservation projects exceeds €1bn, with about 20% being attributed to the development of conservation materials.

So, what will you do? Are you for the demolition of culturally significant buildings of the 20^th Century to be replaced by new construction, or are you for its preservation and conservation? Please give us your feedback!

Features Image by Becca Lavin on Unsplash