Our Buildings Microbiome
It's an interesting time to be involved in architecture. We face many challenges regarding climate change which is putting immense pressure on the industry to change.
Working in the heritage sector, means we spend a lot of time looking to historic methods and materials. We understand we have lost knowledge of traditional materials but it is only when we look back not just 100s of years but 1000s, do we see just how much potential knowledge we have lost.
Looking at truly ancient structures from around the world and the indigenous knowledge of vernacular architecture, we see an astounding array of knowledge, in particular the use of admixtures that greatly modify the mortars and their performance in many interesting ways.
Studies from ancient structures around the world, including China, India, Japan, and Mexico, have discovered the addition of carbohydrates in form of plant sugars, fats and proteins such as egg and aloe vera, in mortars. Predominantly they have been of plant origins but there is evidence of animal as well. The effects of these additives are wide spread:
increased adhesive strength (carbohydrates)
water repellence (fats)
increased durability (carbohydrates, protein)
increased flexibility
viscosity
improved freeze and salt resistance
reduction in shrinkage (protein)
improved workability (protein)
more compressive strength (protein)
There is also evidence to show that the addition of these ad mixes alters the microstructure of the lime which effects density, air content, water retention, setting time and influences the final pore structure and mechanical properties. This can have an effect on capillarity and water resistance.
The fermentation of these added plant materials and the creation of CO2 within the mortar, can force a higher rate of carbonation, specifically deep in a wall where carbonation wouldn't occur because of low air content. There is also the added benefit that when damp enters the mortar, a process of 'good bacteria growth' starts that eats fungus and mould, as well as the development of mycobacterium vaccae in mortars that increases the serotonin production of the occupants of the building making them happy.
What this means for the future
The rediscovery of the lost knowledge of vernacular architecture provides us with a huge potential to make improvements to both our current housing stock and the natural environment. These low energy organic materials can be produced locally and have huge beneficial impacts in creating healthier homes.
The same flora, microorganisms and bacteria we need to flourish in our digestive tracts to keep us healthy may be just as important with our buildings. They can be used to create a health living environment by improving air quality, reducing damp and keeping us warm.
I will be following research with great interest. What an amazing time to be involved in construction!
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