On the Road to Greener Concrete

It’s rare that the opportunity to preserve resources, recycle resources, enhance quality, and improve cost efficiency all come together to deliver an important, improved product that the world uses in abundance every day.

We live on a finite planet with a finite atmosphere, and we have a finite quantity of resources at our disposal. At certain points in history, our human capabilities scale past the point of reason, where our busy work begins to take an excessive toll on planet Earth.

That’s exactly what’s happening in the concrete industry. But there’s a very good story is percolating to the top of the construction world.

Traditional concrete, the building material made from a geopolymer known as Portland cement, isn’t glamorous. It’s not high-tech. It’s not taking us to space. It’s not forming the metaverse – it’s quite the opposite of the metaverse, in fact! Instead, concrete is literally providing the foundation for our real world and for virtually every finished, hardened structure we need to build – our roads, buildings, bridges, and more.

Contrary to popular belief, Portland cement doesn’t owe its name to the beautiful port city in Oregon. Two hundred years ago, the inventor of an earlier version of the material named it after Portland stone, a similar-looking product that was quarried on the Isle of Portland in England.

Today’s concrete has evolved over the years to include lime/clay cement combined with aggregates like clay, shale, sand, iron ore, bauxite, fly ash, and/or slag. Concrete, in the end, is essential that Portland aggregate cement product + water + sand + gravel … all natural resources.

As of 2021, 4.4 billion tons of concrete were produced worldwide, and that number is projected to increase by 25% by 2050.

Researchers are perfecting a variety of eco-friendly, green concrete alternatives made from unique combinations of geopolymer cement components. What makes the resulting concrete “green” compared to traditional concrete products is the fact that each, to one degree or another in the manufacturing process:

1. Uses recyclable material
2. Utilizes a less energy-intensive manufacturing process
3. Generates a lower amount of carbon dioxide (CO2) and wastewater

In addition to those benefits, many varieties of green concrete are proving to be more durable, stronger, and less expensive. They can also be set up quicker with less shrinkage.

All of these are positive attributes, so what’s not to love?

A Better Recipe of Raw Materials

Natural sand is a critical material used in traditional concrete. Natural sand, though, is a limited resource, and it’s also used in the fracking process. This material is mined from open pits, inland dunes, river beds, and other geologically fragile environments. There’s a similar story with gravel, which is another aggregate and another critical component of Portland cement-based concrete.

In contrast, many varieties of geopolymers that make up green concrete use natural fibers and industrial waste products like waste glass sand, fly ash from coal-fired power plants, and blast furnace slag, a by-product of iron and steel production.

Additional research is being done on integrating aggregate from demolition waste and other recycled concrete, forming a closed loop for this important construction material.

A Better Use of Our Energy Resources

At the risk of getting into the weeds and dredging up more detail than you ever wanted to know, green concrete also reduces energy consumption.

First of all, sand mining is very energy-intensive, and any reduction in that activity is a big step in the right direction. Second, the heating process for making traditional Portland cement requires massive amounts of energy. But formulating green cement with fly ash, for example, reduces that significantly.

Reducing Greenhouse Gases

Due to its chemical processes, Portland cement manufacturing accounts for 7% of the global release of CO2, according to the International Energy Agency. If the concrete industry were a country, it would be the third-largest CO2 emitter, right behind the U.S. and China.

Alternatively, green geopolymer cement production can reduce this by 90%. That’s pretty stark, not to mention compelling.

Source link