Why is sustainability important when producing building materials?

Sustainability is a pressing topic for the building materials industry. Currently, the cement industry emits 7-8% of global CO2 emissions, mainly produced by limestone calcination during clinker production. Customers – including public procurement bodies and affluent buyers as well as individuals – are paying more and more attention to sustainability, and there are now international commitments to emissions reductions in Europe, the US, Latin America, and Asia.

Incentivized by these factors, and wanting to preserve our environment, the industry is now pushing strongly to decrease CO2 emissions. Just the other week, over 40 of the world’s leading companies from the Global Cement and Concrete Association announced a roadmap to Net Zero by 2050, including the milestone commitment to reduce CO2 emissions by a quarter by 2030.

“As clinker is the most polluting intermediary material involved in cement production, the two primary solutions for reducing the environmental impact of this production are either to cut emissions from clinker production or to use less clinker.”

So, what are the most effective ways to reduce the environmental impact of building material production?

As clinker is the most polluting intermediary material involved in cement production (with a carbon footprint of about 900 kg per tonne produced), the two primary solutions are either to cut emissions from clinker production or to use less clinker. As a first approach, energy use and emissions can be reduced throughout the process through the use of alternative fuels, such as those based on waste or recycled feedstocks.

As a second approach, raw materials and additives can replace or supplement clinker to produce ‘green cement’. Traditionally, this was done with Supplementary Cementing Materials (SCMs), such as granulated blast furnace (GBF) slag and fly ash. However, these materials are becoming rarer and more expensive. As a result, alternative materials are now being used instead – or in addition – to create enhanced cements. For instance, pozzolans are used to produce Energetically Modified Cements, and calcinated clay to produce Limestone Calcined Clay Cement (LC3). There are also novel cements, based on materials such as belite-ye’elimite-ferrite (BYF) or geopolymers.

These ‘green cements’ produce lower CO2 emissions because of lower clinker content, lower burning temperatures, or lower grinding energy demand. For instance, if clinker is partially substituted for calcinated clays, its activation temperature (750-850°C) is much lower than for traditional clinker (1,400-1,500°C). As such, blended cements like LC3 are set to become the ‘new normal’.

Finally, CO2 emissions from cement production can also be captured for use in various applications, such as synthetic fuels and plastics, or converted into biomass such as in algae.

“Financing is the main challenge when it comes to reducing cement’s CO2 emissions. Digitalization and automation will be key assets to support the financial aspects of this transition.”

And what about the biggest cost pressures facing building materials producers?
Financing is the main challenge when it comes to reducing cement’s CO2 emissions, although new codes, certifications, and incentives such as CO2 credits will help. In general, costs are spiking – for fuel, electricity, gas, freight, and cement itself. To support these cost increases, a wave of investment in infrastructure and housing is coming. Prices of new, ‘green’, premium cements are also likely to rise in the coming years, possibly by over 30%.

To face these challenges, companies will need to meet emerging sustainability demands and supply high-quality products. Digitalization and automation will also be key assets to support the financial aspects of this transition. The good news for cement producers is that solutions to cut emissions will also deliver some cost savings.

How do more sustainable practices also contribute to cost control?
Firstly, the practices I mentioned allow building materials manufacturers to substitute their traditional raw materials, which can be difficult to source and subject to steep price increases, with cheaper alternatives. Not only that, but these substitutions can also achieve fuel cost savings because the replacement materials have lower burning temperatures and consume less grinding energy. In many cases, renewable fuels are also cheaper than their fossil-based equivalents. And CO2 capture can also create some additional revenue. 

On the other hand, manufacturers will also need to invest in new practices to be able to manage their new materials and processes. For example, calcinated clay has a different activation temperature range, and therefore different process requirements.

Why is materials characterization important when implementing these sustainable practices
When dealing with these new processes, products, and materials, manufacturers need to be especially aware of how the changes could affect the final properties of the cement or concrete, as well as its intermediate properties. As such, robust, accurate materials characterization is essential. From stock pile management, production of raw meal, preparation of kiln feed and the production of clinker right through to the final mixing of the end product the control is driven by the elemental, mineralogical composition and particle size analysis.

The latest demands on CO2 emissions drive the use of alternative fuels and the production of blended cements using supplementary cementitious materials like slag, fly-ash, pozzolan, silica fume or calcinated clay. Here, elemental and mineralogical analyses of the intermediate and final products as well as fuels become even more important, while accurate and precise measurement of fineness is critical for optimal grinding.

As an example, for the cement itself, balancing particle size distributions with other properties is very important, as these distributions impact the hydration rate during setting. If particle sizes are low (under 2 microns), your cement will have too short a setting time, with potential cracking, and will need much more water; as small particles hydrate more quickly, they contribute mostly to early strength. Bigger particles (over 32 microns) will not be fully hydrated during setting, reducing the strength of the final product. Typically, the optimum distribution is for 60-70% of the particles to be between 2 and 32 microns. Optimizing the proportion of particles in this size range will maximize 28-day strength (for a given clinker mineralogy).

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Finally, what are the forces that will shape the building materials industry moving forward?
If one thing’s for sure, it’s that the industry is set to change dramatically in the years to come. As already discussed, cement manufacturers are increasingly aiming for improved sustainability. In turn, this is driving process transformation. I also see digitalization and automation – including machine learning – becoming increasingly important in enabling fewer process errors and higher efficiency.

As cement prices increase, concrete is likely to become less of a commodity and more of a specialized product, and demand for ‘green’ products will accelerate. And the industry landscape is also changing: in the near future, I expect to see several mergers and acquisitions, as smaller plants disappear and bigger, more automated plants are built. All these changes will bring new challenges for the industry. At Malvern Panalytical, we are part of this sustainable transition – so we’ll be here to support our building materials customers throughout their sustainability, cost-control, and automation journeys. 

To find out more about how our solutions contribute to sustainability and cost-control in the building materials industry, please contact Murielle Goubard or visit our website.