Tag: Green cement

Counting on … day 88

17th April 2024

Green steel and cement alternatives 

Steel, cement and concrete are major contributors to global climate emissions using manufacturing process that are challenging to green. Therefore one approach to safeguarding the environment is to reduce the use of new steel, cement and concrete. 

This could be by not wantonly discarding things before the end of their lifespan. Where I live, it is not infrequently that someone will buy a house only to knock it down and replace it with a new one. This unnecessarily adds to local carbon emissions. The same can also be true of commercial buildings. Simply demolishing an office building to replace it with another is a poor use of resources. 

Where buildings or other structures are of necessity demolished, the prudent use of resources would see the different building materials being salvaged and reused. Equally before demolishing a structure, consideration could be given to re-purposing the building – upcycling!

The same approach of making full use of an item over its lifespan could equally apply to vehicles, domestic appliances, etc. 

When building new structures, alternative materials with a lower carbon footprint can be used. This might be using timber for beams and columns, straw for insulation, compressed clay for bricks as well as recycling materials from other buildings. However if using naturally renewable resources such as timber, there has to be an awareness of the time frame and forwarded planning needed to ensure an ongoing supply of such materials. Trees may need to be up to 80 years old before being used to create    structural building elements – and that timescale also implies large areas of land being set aside for trees (which is not a bad thing but needs to be planned). 

Did you know you can buy bicycles made with a bamboo frame?  – https://www.nethambamboobikes.co.uk/

Further reading:

The hidden carbon impacts of getting mass timber wrong

https://www.weforum.org/agenda/2021/11/sustainable-mass-timber-green-building

https://www.bbc.co.uk/news/science-environment-61580979

Counting on … day 87

16th April 2024

Green cement – part 2

As part of the need to reduce all greenhouse gas emissions to address the climate crisis, reducing emissions from cement production is essential. 

50% of the emissions come from the release of carbon dioxide as a byproduct during the clinker making process. One solution is carbon capture- capturing the CO2 before it escapes into the atmosphere, pressurising it to a liquid which is injected into rock strata deep underground.  This technology has yet to be developed for use at an industrial scale. 

Another solution is to replace the limestone with an alternative that produces less CO2 – such as magnesium oxide mixed with magnesium chloride solution. However such alternative cements may not have all the attributes of cement when in use – different construction methods may be needed.

40% of the emissions are attributable to the energy needed to heat the clinker kilns. Switching to renewable energy to replace coal is one solution but requires considerable investment in green electricity production and distribution. 

Using materials other than limestone – such as volcanic rock – that can produce clinker at lower temperatures is another possible solution. Another alternative is to replace a proportion of the cement with an alternative binder such as ground granulated blast furnace slag or pulverised fly ash. Again this may alter the properties of the cement and require different construction methods.

10% of the emissions comes from energy used in mining and transporting the raw materials. Energy efficiency and the use of renewable energy will be a way forward.

Further reading –https://theconversation.com/green-cement-a-step-closer-to-being-a-game-changer-for-construction-emissions-126033

(https://theconstructor.org/concrete/green-cement-types-applications/5568/