How often do you come across construction today that does not use concrete? Not many, I suppose. From buildings to bridges and apartments to ducts, concrete holds the strong foundation of our cities today, literally and figuratively. The mass migration to cities that began during the industrial revolution led to an urgent need for quicker and durable means of construction. Eventually, steel and concrete became the most widely used construction material, with about 10 billion tonnes produced every year.

Despite its durability, versatility, and undeniable presence in our environment, concrete is a major contributor to the emission of greenhouse gases and that can only mean bad news for the climate. The building industry today owes a long due apology to nature and using greener substitutes for concrete could lead a long way forward. As architects and designers, we are always reminded of our social responsibilities and pushed to attain sustainable design solutions. 

This article discusses five substitutes that ace the sustainability charts over concrete and can be an alternate solution that offers a lower environmental impact.

1. ASHCRETE

Manufacture of cement, a crucial constituent of concrete, could be held responsible for the productions of CO2 both directly and due to the burning of fossil fuels. Replacing cement with another material could make concrete a much more sustainable material. 

Fly Ash is a by-product of coal combustion that is otherwise discarded into landfills. Ashcrete is a greener alternative to concrete that replaces about 97% of its constituents with recycled material, thus discarding the use of traditional cement. It not only reduces costs but also provides greater strength and durability when compared to traditional concrete. Fly Ash also reduces the shrinkage and permeability of concrete and renders it resistant to alkali-silica reactions. Ashcrete has a wide range of applications and can be used in bridges, pavements, embankments, roads, and buildings. 

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Fly Ash ©www.ashcretech.com

2. RECYCLED PLASTIC

Plastic has an indisputable presence in our everyday life, unlike any other material. The non-biodegradable plastic waste, hence caused, has created havoc in the environment today. The use of recycled plastic in construction is a strategic way out to reduce the emission of greenhouse gases while unclogging the plastic-filled landfills. Plastic waste can be easily recycled and replace 20% of aggregates in concrete. The plastic-filled concrete block thus formed is lighter although its use in taller structures may be questionable.

It may also be noted that only 9% of the total plastic that is produced can be recycled and therefore newer technologies suggest widespread use of non-recyclable plastic in various facades of construction. It is currently gaining momentum in the area of road construction. Nevertheless, re-using plastic would be nothing less than a miracle for our environment. 

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Plastic Bricks Made from Used Water Bottles ©www.expertskiphire.co.uk

3. HEMPCRETE

The hemp plant is a fast-growing renewable resource. To put it in perspective It takes about four months to grow and can be harvested in perpetuity, unlike forests and has little or no demand for water, chemicals or fuel. Hempcrete is a relatively new and biodegradable alternative to concrete. Hemp fibers when mixed with lime and water, create a concrete-like material, but lighter and stronger. Lime releases about 80% less carbon as compared to traditional cement and therefore Hempcrete can be said to test carbon negative. It provides natural insulation and flexibility to the structure. One of the drawbacks of this material is that it cannot be used in load-bearing walls since it takes a long time to cure. Yet, newer innovations have developed hempcrete blocks that can be used as bricks for construction. 

Hemp renders a certain natural texture to the walls which can be enhanced as an architectural quality.

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Hempcrete Walls ©www.archdaily.com

4. FERROCK – STEEL DUST 

Reduce, Reuse and Recycle is the key ‘mantra’ to a sustainable future. Ferrock, a steel-dust version of concrete, uses recycled waste from steel and glass manufacturing industries to create environment-friendly building blocks. It is five times stronger than conventional concrete and can withstand more compression before breaking, making it a potential material that could resist earth movements caused by earthquakes or industrial activities. So what’s more in store for this material? Apart from turning tons of waste steel dust into useful material, ferrock has a greater and greener benefit as compared to cement. It requires a great amount of carbon dioxide while hardening, thus absorbing and trapping the greenhouse gas, which makes it a carbon-negative material. Still in the process of research, it holds the potential to be used in mainstream construction. 

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©www.coolthings.com
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A domed structure made entirely of Steel Dust (Ferrock) ©www.archdaily.com

5. MYCELIUM – MUSHROOMS

If you are not sure you read the heading right, read it again. YES! Mushroom is the next most promising technology that shall reduce our ecological footprint and lead the way into a sustainable world. Mycelium is the root-like fiber from fungi that runs below the ground. They can grow around other organic materials such as straw and when dried and processed can be turned into a building material of any specific shape or form. The mycelium bricks are much lighter and durable, resistant to fire, water and mold. This organic material has wider applications and is only taking baby steps in the construction world. It is currently being used as packaging material, art installations, and other products at a smaller scale. In 2014, a group called ‘The Living’ erected the first mycelium brick tower. The benefits of large scale applications would be countless. 

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Mycelium tower by ‘The Living’ ©www.6sqft.com
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Furniture by Sebastian Cox and NinelaIvanova made from wood chip waste and Fomesfomentarius mycelium ©www.criticalconcrete.com

There are various other natural materials being tested, experimented with and researched to substitute concrete. Bamboo, Rammed Earth, Timbercrete, Clay, Strawbale, Grasscrete, Cork and Wool are some amongst the large pool of innovations. 

The drive towards fostering a ‘cradle to cradle’ approach in the construction industry is integral today. Testing unconventional building materials will only open more possibilities to change to a better future, a rather balanced one. 

Ayushi Desai
Author

Ayushi is a young architect and designer hailing from Gujarat who believes in research driven designs. Cities, Art and Architecture sum up her exploratory drive. She has been working on her research on 'Temporary interventions in Urban Spaces' while running her own free-lance practice in Architecture. Meeting different people, reading books and digging lesser known food joints leave her buzzing.

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