Why is Concrete So Cheap?
Concrete is the most pervasive construction material in the modern world, being used in everything from a small garden shed base to enormous skyscrapers, and one of the reasons for this is how cost-effective it is, but why is concrete cheap?
Well, concrete is made from a few basic ingredients; cement, water, and aggregates, and when it comes to water and aggregates, these are not particularly expensive to obtain. As for cement, there is an element of the economy of scale at play due to the enormous global demand for this construction material.
Of course, this is only a surface-level explanation. If you want to know more about why is concrete cheap, keep reading!
Why is Cement Expensive?
Unlike water and aggregates, cement is not a natural material and requires a pretty involved manufacturing process to churn out the glue that holds concrete together.
The most commonly used cement is called Portland Cement, and consists of materials like slate, clay, shale, iron ore, silica sand, blast furnace slag, chalk, shells, and limestone. These ingredients are heated in a rotating kiln to over two and a half thousand degrees Fahrenheit, which produces marble-sized balls that are called clinkers. These clinkers are then ground down into a fine powder, and it is this powder that is packed into cement bags and sold all around the world.
As you might be able to appreciate, this process is a little more expensive than digging up some rocks or pumping water.
Why Concrete is Cheaper than Cement
Cement itself would be too expensive to use alone on large construction projects, so sand and aggregates are used to make a more economically viable product.
Cement is essentially a very strong glue, and while that glue can act on its own, it is more practical as a binding agent, which is exactly how it is used in concrete. The sand and aggregates are what make up the strength of concrete, and the cement holds it all together. The aggregate needs to be strong, of course, as the finished concrete will only be as strong as the aggregate used to make it, but the important thing is that the aggregate is cheaper to acquire than cement is to make, and so adding it into the concrete mix makes the same amount of cement cover a much larger area.
Sand is essentially an aggregate also, though a much smaller one. For more delicate projects where a smoother finish is desired, concrete may be made with just cement and sand, and no other aggregates at all. Conversely, for larger projects where the smoothness of the concrete is not a concern, a larger aggregate will be used, further extending the coverage of the cement and making the effective cost of the concrete even cheaper.
Economy of Scale
Though the topic of economies of scale is a broad and complex one, we can distill it down to a very simple idea for the purposes of this post. Generally speaking, as long as the raw materials remain as available as they were to start with, the more something is made, the cheaper it can be made for.
For a simple representation of this in action, imagine someone starting a business selling little ornamental figurines. In the beginning, the figurines would have to be painstakingly crafted by hand and may even take longer than would be economically feasible to sell in the long term. However, as business picks up and more figurines are sold, our budding entrepreneur could then invest their profits in the equipment necessary to make a mold of the figurines and use that mold to create future products far more quickly.
Though this is a very simple example, some version of this happens all the time and on enormous scales, and cement is no different. The more cement is in demand, the more it becomes economically viable for cement manufacturers to invest more money into increasingly efficient and fast systems for making their product, and the cheaper the cost of the final product becomes.
And, as far as that demand goes, concrete is the second most used substance on the planet after water, so there is clearly plenty of demand to go around. And, given that water is a crucial ingredient concrete, the demand for concrete looks even more impressive when you consider that a not-insignificant portion of the demand for water is because of the concrete industry.
The Other Costs of Concrete
When we talk about concrete being cheap, we are speaking from a purely financial point of view. That being said, there are other costs to concrete that are significant enough to be worth mentioning here.
The impact of humanity on the environment has become painfully obvious in recent years, with the average temperature of our planet taking a sharp rise that doesn’t match any of the known trends of how climate has behaved historically. Though the severity of this impact is hotly debated in the media, by politicians, and on social media, it is all but unanimously agreed within the scientific community that humanity is responsible for significant climate change. And, though the timescales may be far from agreed, most agree that disaster is on the horizon if things don’t change.
The main vehicle for this climate change is carbon dioxide. Our activities as a species over the last two or three centuries have caused carbon dioxide levels in our atmosphere to soar, which in turn creates a greenhouse effect that causes the temperature to rise.
There are multiple sources of carbon dioxide, of course. We create it when we breathe out, and there are orders of magnitude more humans alive today than there have ever been alive at one time throughout history. Our use of fossil fuels in cars and power plants creates it. We create it by breeding excessive amounts of cattle to feed our numbers. We even reduce the capacity of the planet to absorb this excess carbon dioxide when we cut down trees and develop over natural land.
But what does this have to do with concrete?
It is estimated that concrete is responsible for around 8% of the total carbon dioxide production in the world today. This is an astonishing amount that is all the more concerning when you consider that, if this were the entire carbon dioxide output of a country, it would be the third-highest carbon dioxide output after China and the United States.
Further adding to the negative effects on our environment by concrete is the disruption and damage that is done to areas of land in the acquisition of the raw materials necessary to make it. We also mentioned above how developing over natural areas reduces the planet’s capacity to absorb carbon dioxide because it removes plantlife from the ecosystem. Well, guess what the chief material in those developments is!
Of course, concrete can’t necessarily be blamed for development itself. While there are no doubt areas of nature that have been built over largely because the low cost of concrete made it an economically viable project, it is the unceasing expansion of humanity that is the driving force behind it. That being said, it is hard to ignore the impact of concrete on our environment, and it could well be an industry that is not sustainable in the distant future, not because of economics or resources, but because the environment simply can’t take it.
Scary stories about our environment aside, there is no doubt that concrete is by far the most widely used construction material in the world today. There is an element of the snake eating its own tail to this—concrete is widely used because it is so cheap compared to the alternatives, but its widespread use drives the price down, making it more appealing for new construction projects.
There are other factors in the cheapness of concrete, of course, such as the use of relatively inexpensive raw materials for aggregates, which actually make up the majority of the concrete mix. As long as the raw materials used in concrete remain as readily available as they are today, there is no reason to believe the relative cost of concrete will rise while the demand continues to be so high.