The CVBT was founded in one of the poorest areas of Thailand: “Since 1991, the CVBT has been using, researching, developing and promoting small-scale building material manufacturing technologies as a means to create new employment for villagers.”
Some of the technologies include compressed earth bricks (CEB), cement that incorporates readily available waste materials such as rice husk ash and a variety of presses for making tiles and paving blocks. Read on…
I found the bit about rice-husk-ash cement to be the most interesting. Rice-husks are burnt at a low temperature so the remains can be ground with a mill into a fine powder. This can replace up to 30% of the conventional Portland cement required and apparently with the same resulting strength. Reading more about the technique here (link), Rice husks are a pozzolana or a natural cement due to their high silica content. Rice husks also make a good biomass fuel for heating or energy, it may even be possible to produce a cost-effective silicone for photovoltaic solar panels. (link)
The hardest part of the process is milling the ash into a suitable powder. The CVBT have also designed a low tech mill (which you can see in the previous link) but effectively this is the same kind of process you hear about with coal power stations capturing and using their ash on a bigger scale. (link)
The CEB press they use is similar to other ‘CINVA’ rams – which is probably worth a post on it’s own. (but here’s a good summary in the meantime!)
This video demonstrates making a basic block with some rice ash compared to a CEB without (thanks naturalbuildingblog.com)
More inspiring uses of waste materials. Anyway, that’s it for now, don’t forget to subscribe for more!
(PS, It’s LESSBIG’s 100th post by the way. We don’t do ceremony round these parts. Also I forgot about it. See you at 200 posts!)