Concrete, as we know it today, is a mixture of cement, water, and some aggregates along with it. After Portland Cement was patented in 1824, concrete came out to the world as one of the most useful materials ever made by human beings. Now, it's leading the construction industry from the front by being the most durable building materials. It provides good fire resistance, and structures made of concrete have a long service time. But, to go along with the endless list of positives of concrete, there are a few negatives as well. Let's find out more.
The traders may have built the first concrete structures in oases of Southern Syria around 6500 BC. These traders kept the concrete as dry as possible as excess water weakens the concrete. By 700 BC, they figured out how to build kilns to produce material for the construction of concrete floors, rubble-wall houses, underground waterproof cisterns, etc. These cisterns were kept secret and probably were why these people were able to thrive in the deserts of Syria.
The Egyptians, later in-3000BC, used gypsum and lime mortars in building the pyramids. The bedding material used in the Great Pyramid of Giza was 500000 tonnes of lime mortar. The mortar was used for casing stone which is the visible surface of the pyramid. Around the same time, the Chinese were able to build the Great Wall of China using a particular kind of cement which was also used in boat building.
Later came the Romans, who are considered the masters of cement and concrete. By 200BC, the Romans were building very successfully with material like cemented rubble. They have created many beautiful structures like the Pantheon, Colosseum, and numerous arches and domes.
Concrete is the most used human-made material ever. It's the second most consumed substance after water. Every second, over 3000 bathtubs of concrete are used for construction. Concrete production has increased more than 30 folds since 1950 and almost four-folds since 1990. China used more concrete in 2011-2013 than the USA in the 20th century. All these numbers say concrete is one of the essential materials in the modern-day. It is the foundation of modern development, roof for billions of people, strengthening us to fight the natural calamities, and providing structure to significant buildings like schools, hospitals, etc.
So, why are we speaking these numbers? Why are we calculating the amount of concrete which is helping humans in such a notable fashion? It is because one of the chief nature of the concrete is to harden and degrade dangerously slowly. Then why is it less discussed than plastic?
It's because it's not getting found in the stomachs of animals, its traces aren't found in our blood, we don't see it in every other trash.
Not degrading is not the only problem with concrete. Concrete is a dominant contributor to global warming and other climate crises. If concrete were a country, it would be the third most CO₂ producer only after the USA and China. The main ingredient in concrete is cement, which is produced by a kiln which requires a tremendous amount of fossil fuels which in turn contributes to CO₂ emission. This is not the only way in which the concrete industry produces CO₂.
Half of the CO2 emissions in the production of concrete come from the reaction that breaks up the calcium carbonate into CO and CO₂, and the other half from the fossil fuels required to heat the kilns and transport the materials. Concrete accounts for about 8% of total CO₂ emission. This might not sound much compared to other industries such as transportation, electricity, agriculture, but researchers have already come up with a few gripping solutions to this concrete situation.
It's almost unbelievable sometimes that with some research and innovation, what feat we can achieve. One example is CarbonCure's concrete. Its innovative system injects CO₂ into the concrete as it's being mixed. When the concrete hardens, those otherwise harmful emissions are sequestered forever before it even enters our atmosphere. CarbonCure converts the CO₂ into a mineral which itself helps to strengthen the material. So, now, we will be able to use less cement in their mixture and still get the same strength. With its innovative technology, CarbonCure has saved over a hundred thousand tonnes of CO₂ produced. The best thing about CarbonCure is, it comes at the same cost as the standard concrete which we use!
There are multiple other alternatives such as ashcrete, greencrete, mycelium, etc. But these materials are new and can't account for the same strength that concrete promises.
With everything said, there are multiple arguments against concrete, and many of which show us why using concrete is necessary. But we must control concrete from growing into a highly polluting industry like plastic. The recent increase in concrete consumption and the predicted increase in consumption in coming years only acknowledge the fact. CarbonCure and other innovations such as this can make the burden less on nature to sustain.