Dirty Secrets of the Concrete Industry

Until recently, concrete was viewed as a strong motive in creating civilizations throughout history, and an enabler for their economic and social growth[ScienceAlert]. However, when the environment movements started in the 1960s to warn the world about air-pollution caused by modern industries, the image of concrete changed in eyes of the public, and it got the reputation of being evil to the environment.

Many people jump to conclusions and judge the concrete industry without knowing the history behind it, which can explain a lot of its present. Before we make a final decision, we need to consider the advantages as well as the disadvantages of the concrete to reach a fair and wise decision about it.

“Portland-Cement accounts for about 7% of all global carbon emissions[E&ENews]”, we need to put our emotions aside to analyzing such a statement. Of course, the environmental impact is catastrophic, but we should notice that the problem is related to cement and not concrete. Additionally, the argument is built on Portland-Cement, and doesn’t generalize the impact to all types of cement!

Almost 2000 years ago, Ancient Rome started using concrete as a building material all over the empire[BillWarch]. The high strength, water resistance, and durability of concrete drove the Roman extensive use of concrete; however, the Roman concrete contained only rocks, seawater, volcanic-ash, and lime[ScienceAlert]; No cement at all!

The Concrete is an outcome of mixing water, aggregate, and cohesion material in an environment-friendly infinite chemical reaction, which explains why concrete gains strength over time[PCA]. As we can see, cement isn’t a requirement in that reaction; however, the Portland-Cement is the commercial cohesion material that has been

used in the concrete production for the past 200 years[E&ENews], after it was introduced to the world by Joseph Aspdin, and now it accounts to 95% of the entire cement market[BuildingGreen].

Seeing the Glass Half Empty:

The production of the Portland-Cement is based on harsh chemical reactions of silica sand, limestone, clay, and chalk, under a high temperature (1400 C)[The Guardian], releasing massive amounts of CO2 in the air; 1 ton of CO2 is released to produce 1 ton of Portland-Cement[BuildingGreen], where the fossil fuels burned in the process release 70% of total CO2 emissions of the production, while the other 30% is a result of the silica reaction[GreenAge].

Compared to other industries, the Portland-Cement production is easily-executed, which explains the widespread use of the product[CivilEngineering]; the Portland-Cement has a yearly global production of 3.8 million cubic meters[TheConstructor], China is responsible for 50% of that number[GreenAge], and the production is expected to increase by as much as 23% by 2050[E&ENews].

Seeing the Glass Half Full:

Even that the previous numbers are shocking, but concrete still has many advantages over other building materials; concrete is more economical compared to steel and wood[CivilDigital]; concrete has the ability to reduce the energy used for heating and cooling up to 29% compared to other building materials[CivilDigital]; the concrete production can have 10 times less energy consumption of

the steel production[CivilDigital], and surprisingly, concrete consumes CO2 from the air, absorbing 43% of its original CO2 emissions in the long run, which made many scientists argue that concrete is a green building material[E&ENews].

The Real Issue:

Clearly, the problem of air-pollution of concrete isn’t technological; it is purely legal, and conceptual. A paradigm shift is needed in the current architectural mentality which drivers the commercial use of concrete. We have been using the material for so long and that developed a level of confidence in the current version of concrete, which makes switching to other kinds of concrete psychologically challenging, so we need to start encouraging the smart use of concrete and repurposing it in our designs[E&ENews].

The other challenge is not only the lack of environmentally-strict regulations, but also the lack of policy incentives to create pressure on cement manufacturers to adopt new technologies[E&ENews].

Such an implementation needs also to be supported by the scientists’ community which is the reason behind the world’s most powerful and influencing building codes are still being based on the chemistry of the Portland-Cement[E&ENews].

Concrete is a usefully unique building material that fits our building needs[ASCE]. Whether it’s a historical building like the Roman Pantheon’s cement-free dome[ScienceAlert], or a modern structure like the reconstructed interstate-35 bridge in Minneapolis [TheGuardian1], proofs of the possibility of switching to an environment-friendly concrete are all around us, only if we choose to look!