You must have heard that everything old is new again. Well, that is just what is happening with rammed earth construction. This method of building dating back thousands of years ago is undercover in revival. But why? Because it is imbued with remarkable benefits for sustainability, energy efficiency, and resilience. And researchers from UBC Okanagan are leading in this revival, whose work paves the way into a green future.
So what happens in rammed earth construction? Basically, that’s a process by which an aggregate of soil, sand, and clay is compacted into a solid mass to form walls. This only takes local materials so they are, therefore, eco-friendly, not requiring too much of an energy-intensive manufacturing process to prepare. But it is more than just mixing dirt and clay.
Now, a new exciting development, according to acting civil engineering professor Dr. Sumi Siddiqua, who is a lead researcher in the School of Engineering at UBC Okanagan, is the use of wood fly ash as a cement supplement. “Industry has been trying to find uses for materials such as fly ash that are mainly sent to landfills,” says Siddiqua. “Using local earth and rammed-earth products eliminates the need to exploit sand. Equally as important, this material is also less affected by wildfires compared to current wooden structures.”
Because it is a by-product of pulp mills and coal-fired power plants, fly ash can have high strength and texture features close to those of cement. That makes integrating it into rammed earth construction very promising for the cause of sustainable building practices. And this manages waste, besides giving a resilient building material.
It’s all part of an effort by the Build Better Cluster at UBC, in collaboration with BC Housing, to begin using construction methods with rammed earth in new homes as a collaboration with Indigenous communities. The method also helps offset a global shortage in the construction of sand, not the kind one would find at the beach. Builders are always looking for cheap and ready-to-source materials that can replicate the traditional strength of cement. Fly ash ticks those boxes.
“Everything old is new again, and that is precisely why we’ve been investigating rammed earth construction,” says Dr. Siddiqua. “By incorporating industrial by-products, we’re meeting a growing need for readily available construction materials, while being sustainable in the process.”
It has been found that the use of fly ash improves the properties of the structure, and the material can be applied to regions with varying climatic conditions, including load-bearing, non-bearing, and isolation panel walls. It can also be found even remotely, and that it boosts the insulating properties of insulating materials.
Though a massive boom in rammed earth homes is unlikely to happen right away, use of fly ash in composite cements is already one area that is beginning to attract serious attention, says Dr. Siddiqua. “There is increasing demand for sustainable building products here in Canada and around the world, and materials like fly ash are just the beginning of a new and important trend,” the researcher said.
Therefore, what are the practical advantages of rammed earth? Most rammed earth walls are high in thermal mass, which allows them to absorb and store heat. This can also achieve high energy savings over the lifetime of a building. Besides, the material has a great resistance to damp, wind, and other elements, not to talk about hundreds of years of life with little care.
But, like every other construction process, rammed earth has its difficulties. It is very skill and equipment-intensive, hence much costlier and extremely time-consuming as compared to conventional means, such as concrete. Besides, it tends to hold possibilities of cracking if not properly compacted or under very great loads. It is often reinforced with materials like steel or concrete in earthquake-prone areas.
Nonetheless, of this, the environmental benefit associated with rammed earth is very hard to ignore. To a great extent, this is, conversely, what makes this material rather quite an interesting option for those devoted to green living: the low ecological impact, energy efficiency, and durability this very material inherently is. With more builders and homebuyers becoming interested in eco-friendly construction materials, rammed earth with fly ash can get together.
Here are some tips if you are looking at using rammed earth in your next building project: All you need to mix in are the right proportions of clay, sand, and silt, plus a bit of aggregate like small stones or gravel. Next, wet your mix so that it’s workable. Then you would have formwork to contain the mix in place as you compact those layers; hopefully not until it reaches that height.
Repairing of rammed earth does not require much care. With regular checking and protection from water and tough chemicals, your rammed earth structure is well maintained. In fact, noticing crack lines, you have to fix them immediately to avoid further decay.
Rammed earth technology, therefore, serves as a more sustainable, energy-efficient, and resilient alternative to traditional building materials. Though it demands special skills plus committing a massive upfront investment, considering the long- term benefits, this RAM technique currently is the most thrilling option available for eco-friendly people and professionals from the building/architecture background. As Dr. Siddiqua puts it rightly, “Materials like fly ash are just the start of a new and important trend” in sustainable building practices.
