Reusing Concrete

Concrete is everywhere in the urban environment.  It is the building block of the 21st century and does not appear to be going anywhere anytime soon. As a natural builder, it is hard to be a fan of a material that has such an enormous level of embodied energy. That being said there is definitely a place in natural building for concrete, particularly in dense urban areas. It is hard to find a better material for foundations and as the saying goes all buildings need a good hat and good boots. When properly thought through and designed, the use of concrete can be minimized and go a long way in ensuring an earthen structure is here for a long time.

What is quite exciting about concrete for me though is being able to use it again and giving it a second life. You may have heard of recycled concrete referred to as urbanite. Urbanite often comes in 3-4″ slabs that are harvested from old driveways, sidewalks, or porches. You can use it for foundation work, retaining walls, patios, or even just “filler” in structures. There are quite a lot of options and a quick look around the internet will certainly get you inspired on the many possibilities of urbanite.

I’ve primarily used urbanite for foundations and retaining walls. In some cases, the client has wanted to disguise or hide the urbanite all together. That is fairly easy to achieve by using another material like cob or a veneer stone such as Colorado Red Flag Stone. By using the urbanite as essentially “structural fill” you save money and can feel good about using a material that would otherwise would be a waste product or destined for another high embodied energy processing facility.

Yet, there is certainly something beautiful about a well laid, dry-stacked urbanite retaining wall.

Hidden Urbanite Foundation
A foundation for a cob bench. Local granite stone was used for the front of the bench. Urbanite was used for the less visible backside of the bench.
Urbanite Foundation
Urbanite foundation that would later be hidden with cob and Colorado red flag stone.