Is volcanic ash the key to stronger and greener concrete?

Could our future buildings be constructed out of cement mixed with volcanic ash? This is what scientists from the Massachusetts Institute of Technology and Kuwait Institute of Scientific Research have been trying to find out by analysing how adding volcanic ash could potentially reduce energy costs during production and create stronger concrete mixes.
Increased strength
Volcanic ash was an ingredient used by the Romans in the mixing of their concrete over 1,500 years ago and many of the resulting structures are still standing today - a testament to the mixture's durability. Research found that pulverizing the volcanic ash down into finer particles and mixing with cement produced stronger concrete structures than regular cement used today. However, reducing the volcanic ash down to smaller particles used more energy, so to achieve stronger concrete, there must be a trade off with the amount of energy used to create it. Researchers argue that this gives concrete manufacturers the flexibility to customise their concrete, saving a lot of energy on jobs that don’t need to prioritise strength.
An environmentally friendly additive
Volcanic ash is largely considered a waste product and is in abundant supply and easily accessible in multiple locations around the world. In normal concrete production, rocks such as limestone need to be removed from quarries and further crushed and heated at very high temperatures to be used in cement. Volcanic ash on the other hand has already undergone this process naturally, greatly reducing costs needed to prepare it for use in cement.
According to the findings, which were published in the Journal Of Cleaner Production this week, the new ready mix concrete consisting of 50% volcanic ash and 50% regular cement would take 16% less energy to construct a neighbourhood of 26 concrete houses in comparison to regular Portland cement. Concrete production is the second most widely used building material after water and accounts for 5% of the world’s overall carbon dioxide emissions, the potential for volcanic ash as an additive to ready mix concrete is therefore a huge step towards overall greener concrete production.
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