When the cement concrete was first invented, it was no less than a revolution. This new grey colour material was so amazing to use in construction with extreme compressive strength, rapid hardening feature and low maintenance that every road, building, bridge and dam was built using concrete. The use of rocks and wood was just laid-back and concrete became the most prevalent material in construction history.
Concrete remains alive even today in the modern world of smart cities. But as the world has woke up to know that some man-made inventions of the past are bad for the environment, hence ways to compensate are coming through.
As a safer replacement to the conventional concrete, geopolymer concrete also regarded as ‘green’ concrete is anticipated to be the new revolutionary trend in smart city constructions of tomorrow. Really? Let’s find it out!
The First Geopolymer Concrete Trial In The World
This year in 2019, the city council of Sydney in Australia partnered with the University of New South Wales to replace a portion of roadway in the city with green concrete. This initiative is taking shape with the aim to test the viability of green concrete in the construction of roads.
A similar project was brought to reality in the town of snug in Tasmania, the island state of Australia by using landfill waste and used plastics, popular as the ‘plastic road’.
However, in terms of the usage of the materials, the new project is different. Sydney council has revealed that the world’s first ‘green’ concrete road material will be reprocessed from the industrial waste of coal-fired power stations and steel manufacturing industries.
As per the university, this green concrete which is a geopolymer concrete produces only 300kgs of CO2 per tonne of cement as opposed to the conventional concrete which generates 900 kgs of the carbon emissions. But what makes it happen? Its the composition which consists of a mixture of concrete and recycled materials.
The savings calculated are equivalent to the electricity consumed by an average household every half a month.
The new project will begin testing the durability of geopolymer concrete on Wyndham Street in Alexandria which leads to Sydney Airport. Nine sensors have been equipped there to monitor the performance of the concrete and compare the results. The university researchers will monitor the road performance for up to five years. Going ahead, the results from the testing will be used by the University of NSW and the Cooperative Research Centre for Low Carbon Living to draft the first set of industry guidelines for the use of geopolymer concrete.
Although research on the geopolymer concrete began in the 1990s, its viability as a slightly environment-friendly product in commercial construction was not explored until now.
The low-carbon concrete unfolds the possibility to use 400 million cubic tonnes of globally recorded waste from the coal and steel industries in a green manner. More importantly, it is using the waste from the industries which are one of the highest producers of carbon emissions globally.
Clover Moore, mayor of Sydney is proud that the city of Sydney is the first carbon-neutral local government of Australia and the authorities are constantly making strides in reducing the carbon footprint. Further, she said that projects like this can result in new products that help in reducing carbon emissions. Local governments play a responsible role in maintaining local roads and so if more environmentally friendly materials are used in developing the infrastructure of the city then it is possible to fight climate change.
Is Geopolymer Concrete An Ideal Choice For Road Construction?
In the conventional form of concrete, Portland cement is the basic ingredient, used as a binding agent and is the most extensively manufactured artificial material in the world. At present, its production is over 2.6 billion tonnes a year and the number is growing at 5% annually.
Therefore, in an attempt to stop the concrete and cement from harming the pollution further, Dr Erez Allouche, assistant professor of civil engineering at Louisiana Tech University and associate director of the Trenchless Technology Center is executing innovative research on geopolymer concrete. Alongside, the research also focuses on the ways of using a waste byproduct from coal-fired power plants.
The Characteristics & Benefits
As a greener approach, geopolymer concrete uses ‘fly ash’ as a replacement for Portland cement. Fly ash is one of most abundant industrial by-products available across the globe. The use of fly ash has a huge impact on the strength of the material. Alternatively, the concrete may also use rice husk along with the binding agent which is not cement.
Owing to such ingredients, geopolymer concrete has potential benefits including a reduction in carbon emissions, use of wastewater and savings in energy consumption.
The new age concrete is better in producing a durable infrastructure that can stand strong for centuries, instead of decades. And the use of fly ash can lead to conservation of land which is presently used for disposal of coal combustion products. In this way, fly ash can also be prevented from entering the waterways and contaminating it.
Furthermore, if we compare Portland Cement and geopolymer concrete, the latter performs better in terms of resistance to corrosion, fire (up to 2400°F), and acid. Even in the case of sulphate and magnesium, it exhibits excellent resistance. Other benefits include higher compressive and tensile strength, quick strength gain and lower shrinkage after drying. In fact, researchers believe the geopolymer concrete’s greatest advantage lies in its life cycle greenhouse gas reduction potential, as far as 90% as compared to Portland Cement. It decreases the carbon dioxide release in the atmosphere and hence its widespread usage can have a visible impact on the environment.
The Economic Benefit
Considering the cost of the geopolymer concrete it is essentially low than the traditionally used concrete. The cost of one-ton fly ash is just a fraction of the cost of one-ton cement. Although the investment that goes in alkaline solution is a little bit more, the total cost of the new concrete is approximately 10% to 20% less than the cement-based concrete of the same quantity.
Therefore, it ticks all the boxes on in being the innovative and sustainable construction material of the future.
Geopolymer Concrete Is Not A New Technology
It’s quite surprising to know that geopolymer concrete which we call it as new or innovative concrete is not new to human knowledge. Its use began from the time pyramids were constructed i.e thousands of years ago. However, the benefits and facts about this material came to attract the researcher’s interest recently.
The term ‘Geo-polymer’ was minted by Prof. J. Davidovits in 1978. He discovered a phenomenon that the polymerisation process happens through substantially rapid chemical reaction under alkaline environment.
In the end, research suggests that due to the excellent properties of geopolymer concrete, it can prove to be very useful construction material, particularly for rehabilitation and retrofitting. Even more, it can be sustainably used in road works, owing to the fact that it achieves strength very quickly.
The green concrete is already being tested on one of the roadways in Australia and it will soon demonstrate its practicability in terms of performance, durability and cost.