THE PARADOXICAL REALITY OF CONCRETE
Climate
The very material that builds our world is also destroying it. How shall we address this catastrophe?
Concrete is a building material composed of a hard and chemically inert substance known as ‘aggregate’ (formed by integrating various kinds of sand and gravel) that is bonded together by cement and water. After water, concrete is the most widely used substance on the face of Earth: know that by the time you read this sentence, the global building industry will have poured more than 19,000 bathtubs of concrete, and in the time it takes you to go through this article a few times, the volume will fill the Albert Hall and spill out into Hyde Park (amounting to more than 86,650,000 liters)!
Although concrete closely pursues water in the extent of its usage, its precursor merely dates back to 1300 B.C when the Nabatea of modern-day Syria and Jordan pioneered its manufacture to erect structures that have survived to this day even. Later in 1756, a British engineer named John Smeaton invented modern concrete (or hydraulic concrete) by adding pebbles as a coarse aggregate and mixing powdered brick into cement. However, it was observed that this type of concrete had a high density, rendering even small structures built from it to be practically immovable. Hence, finally reinforced concrete was developed by Joseph Monier, an unschooled Parisian gardener who made garden pots, in 1849 while he sought a solution to make his concrete pots lighter to be able to easily move them. Oblivious to the science behind it, he discovered that a combination of iron and concrete made a strong but relatively light material that could be used to build all types of structures: from his small pots to gigantic skyscrapers. Even to this day, this type of concrete is used and has helped shape the modern age — literally.
Concrete is crucial to civilization on account of a number of reasons. First and foremost, concrete is how we seek to tame nature. Through its relative affordability and availability, concrete extends millions a roof over their heads, keeping them from rain, cold, dust and even climatic uproars. Concrete is also a simple material — so simple that with a lone concrete mixer accompanied by moderate help, anyone can set up a concrete house. Under summer sun, concrete also keeps things cool, while in winter it retains heat to sustain a cozy environment inside. Moreover, concrete is modernism, and modernism is concrete. It has helped us to metamorphose this formerly desolate world into bustling cities and megacities with assorted structures: houses, offices, subways, airports and even towering skyscrapers, which create living space out of thin air!
But these benefits have come at a cost: a cost that could even outweigh the combined merits of concrete. In recent years, it has transpired that concrete utilization may presage a climatic and environmental calamity, leading to a potential termination of life. For one, concrete is a thirsty behemoth, sucking up virtually a 10th of the world’s industrial water use. This often inhibits water supply to drinking and irrigation since 75% of this consumption takes place in drought-prone and water-scarce regions. Besides, concrete is also known to augment the heat-island effect in cities. It soaks up radiation from the sun and traps toxic fumes emanating from car exhausts and air-conditioner units to gradually lift up the mercury thread for the environment. Though it is better than the darker asphalt in this respect, it may still harbinger a potential heat-stroke. Next, concrete compounds the problem of silicosis and other respiratory diseases. The dust that arises from mixers and windblown stocks contributes as much as 10% of the coarse particulate matter. Limestone quarries, cement factories along with trucks that ferry materials between them and the construction sites all cause air pollution as well. Furthermore, at a large scale, even the acquisition of sand from beaches, etc. to form cement can be perilous; this form of mining is exponentially run by organized crime gangs and incorporates murderous violence. Lastly and perhaps most importantly, concrete is said to be responsible for climate change. It accounts for 4–8% of the world’s CO2 emissions, and shockingly half of it is produced during the manufacture of clinker alone, the most energy-intensive part of the cement-making process.
In light of the above argument, it can be concluded that concrete is not as safe as one might consider it to be. However, even after experiencing this epiphany, it fills us with ambivalence as to whether we should abandon it, or proceed with it in the same manner as currently. Conceivably, none of this alone is rewarding. Rather, we should choose both: that is, finding out the intersection where we can achieve the maximum from concrete without compromising on the environment. One way to attain this delicate balance is through modification of concrete, for example, low-carbon approaches to concrete-making that are already being pursued. Hopefully, such methods will eventually be able to find their way into the industry.
