What ‘Concrete’ Steps Can We Take to Decarbonize the Construction Industry?

What if the fundamental materials we use to construct our cities could be reimagined to fight climate change?

The construction industry stands at the frontline of the battle against climate change, responsible for a staggering 37% of global carbon emissions. But this also means that the industry has the greatest potential for positive change and innovation!

On construction sites, there are lots of emissions-intensive processes, requiring a lot of energy. The most widely used construction material, cement, is a huge contributor to releasing these carbon emissions. But there are solutions to these alarming concerns, and this one is going to be all about that.?

Sadly, Buildings produce a lot of Carbon!

Today, cities are described as ‘concrete jungles’. This shows how commonly concrete (made primarily with cement) is used, mostly for its versatility and cost-effectiveness.

Traditional concrete production & cement both account for about 9% of global carbon dioxide (CO2) emissions. This is primarily due to the calcination process in cement production.

Cement is the second most consumed material on the planet, the first being water. The sheer scale of its use is staggering, making the problem of carbon emissions even more daunting.

During calcination, limestone (calcium carbonate) is heated in a kiln to high temperatures, which releases carbon dioxide gas and produces lime (calcium oxide). Chemically, this reaction is represented by CaCO3 → CaO + CO2.?

Each kilogram of cement we produce emits approximately 0.9 kilograms of CO2. Cement has now become the second most widely consumed substance for humans, second only to water! Considering the vast amount of cement used globally, this translates to billions of tons of CO2 emissions every year.

The situation is further exacerbated due to increasing urbanization. There is an increasing demand for building materials, resulting in increased concrete demand, and hence more CO2 emissions.?

But what if there were alternatives to traditional concrete? Could we reduce our reliance on this carbon-intensive material while still meeting the demands of modern construction??

How can we Lower Carbon Emissions?

Recent innovations in building materials have focused on reducing their environmental impact. Many of these materials sound promising, with many properties and characteristics matching that of concrete, without the harmful effects. Here are a few examples:?

Hempcrete

One such material is Hempcrete, made from lime and hemp (a natural plant fiber). It is not only lightweight and durable but also has excellent insulation properties. More importantly, hemp plants absorb CO2 during their growth, making hempcrete a carbon-negative building material.

Hempcrete, however, has a lower compressive strength compared to traditional concrete, typically around 2-3 MPa versus concrete's 20-40 MPa, making it more suitable for non-load-bearing structures.

Cross-Laminated Timber (CLT)

Another promising material- cross-laminated timber (CLT), made by gluing layers of wood together at right angles, creating a strong and flexible material suitable for various construction applications.

Wood, being a natural carbon sink, stores CO2 throughout its lifecycle, making CLT a sustainable alternative to traditional construction materials.

Apart from material alternatives, the industry has also innovated the process of manufacturing cement and concrete to reduce its carbon emissions.?

What is Carbon-Absorbing Concrete & how does it work?

A revolutionary new material designed to reduce concrete's environmental impact,carbon-absorbing concrete incorporates recycled aggregates and carbon-sequestering additives that actively capture and store CO2 from the atmosphere.

‘Supplementary cementitious materials (SCMs)’ like fly ash, slag, and silica fume, are the by-products of other industrial processes that can be used in the production of concrete. During the curing process, these materials not only absorb CO2, but also strengthen the concrete. They make concrete a more sustainable option for construction projects by reducing its carbon footprint.?

Carbon-absorbing concrete can be used for everything from building foundations to pavements, giving the industry a versatile solution.

What can Carbon Sinks do for Construction?

A carbon sink is a natural or artificial reservoir that absorbs or stores carbon dioxide. Forests, soil, and oceans are examples of natural carbon sinks, while engineered solutions include biochar and carbon capture and storage (CCS) technologies.

Biochar, for example, is a type of charcoal that, when mixed into concrete, can help trap and store carbon dioxide, keeping it out of the atmosphere. CCS technologies, on the other hand, capture CO2 emissions from industrial processes and store them underground, preventing them from being released into the atmosphere.

In construction, urban green spaces and green roofs also act as carbon sinks. This environmentally friendly infrastructure not only absorbs CO2 but also provides additional benefits such as reducing the urban heat island effect, improving air quality, and benefiting the environment.

How can India's Construction Industry Reduce its Carbon Footprint?

India faces a unique challenge in balancing sustainable development and rapid urbanization. As for India's construction sector, that means cutting carbon emissions while also upskilling workers, as it provides jobs to more than 59 million people in India.?

Governing policies and initiatives play an important role in promoting sustainability in construction & maintaining the employment of workers. The Indian government has introduced various policies to promote green building practices, such as the GRIHA & IGBC certifications. Eco-Niwas Samitha, developed by the Bureau of Energy Efficiency (BEE) in 2018, is an example of an energy-conservation residential building code aimed at promoting energy-efficient design and low-carbon construction.

Such certifications encourage and promote the design community to create better green buildings. In addition to government initiatives, private sector involvement is essential for achieving large-scale impact. ?

It’s More Than Just Decarbonizing!?

The construction industry has made considerable progress towards decarbonizing, but there are still several challenges to overcome.

Small-scale construction firms often find it difficult to adopt sustainable materials and technologies because of the higher upfront costs. With more awareness and accessibility to information, this scenario can hopefully be altered. Working together, designers and industry stakeholders can develop and implement strategies that reduce carbon emissions and promote sustainability.