Concrete, by itself, is a very durable building material. Rome’s Pantheon is a magnificent structure. It is the world’s highest unreinforced concrete structure, and it is still in its excellent condition, even after 1,900 years of existence. Yet, many concrete buildings of the last century collapsed, from bridges and highways to homes. Most concrete structures built this century will get damaged before its expected end of life.
This might seem strange given the existence of antique structures. The critical difference is that today’s construction process integrates the use of reinforced steel concealed inside the concrete, which is known as the rebar. Steel is made primarily from iron and one of iron’s unalterable characteristics is that it rusts. It destroys the integrity of concrete structures. That’s also the reason why it is expensive to repair them.
Steel and Concrete
Steel restructuring was a remarkable achievement of the 19th century. The steel bars add strength, allowing for the construction of tall, cantilevered structures and smaller, less backed slabs. It speeds up building times, as these slabs need less water to pour.
Such principles, encouraged by the assertive, and sometimes repeat promotion of the concrete industry during the 20th century, led to its massive popularity. Reinforced concrete is competing with more durable building materials like steel frame and the traditional bricks and mortar. It has substituted environmentally sensitive, low-carbon alternatives around the globe, such as mud brick and rammed earth. These traditional practices may also be the most sustainable options.
History of Reinforced Concrete
Early 20th century architects claimed that reinforced concrete is expected to last very long, perhaps for a thousand years. But in reality, they only last for 50 to 100 years, sometimes even less. Local building codes generally allow buildings to last for many decades. However, deterioration may begin in as few as ten years.
Many architects and engineers point to the natural relationship between concrete and steel. They have identical thermal expansion properties, and the concrete’s alkalinity may help resist corrosion. But there’s still that lack of information and knowledge about their other properties in relation to temperature changes that are associated with sun exposure.
Why Use Steel?
The various alternative materials that can be used for concrete construction, like stainless steel, fiber polymer composites, and bronze aluminum aren’t commonly used still. Developers find the ease of reinforcing plain steel to be much more appealing. But many developers and designers refuse to consider the ongoing costs of concrete repair, replacement, or maintenance.
There are strategies that can solve the steel corrosion issue, like cathodic protection, where rust-inhibiting electrical currents hold the entire structure together. There may also be new interesting approaches for monitoring corrosion, which is done by acoustic or electrical means.
Hiring Qualified Concrete Experts
It is difficult and expensive to recycle concrete. Over time, reinforced concrete decreases its strength and may catalyze certain chemical reactions that accelerate its decay. The world needs to reduce its concrete use but this will not be possible without constructing long-lasting buildings. If you need more information about concrete, click here.