How Hempcrete is made
Hempcrete is made using the wood-like core of the industrial hemp, called the hurd, mixed with a lime-based binding material. This core is high in silica content making it able to bind very well with lime, a rare quality among plant-based material. This results in a lightweight cementitious material weighing 1/8th of concrete and capable of floating in water!
The use of the hemp stalk is desirable because many other parts of the hemp plant, like seeds, are grown for use in so many other applications that the stalk is forgotten and discarded as a waste product. This means that as hemp production increases for other uses (e.g., USDA certified organic hemp oil, food, etc.), the availability of hemp stalks increases while costs decrease.
How Hempcrete is used
Currently, hempcrete is carving out a niche as a building material, particular with respect to walls. Hempcrete technology has not reached the point where it is as strong as traditional concrete, but it can be used to infill or otherwise coat the walls of structures ranging from commercial buildings to residential homes. Essentially, hempcrete is typically either formed into blocks then used to build, or, more commonly, blown into or otherwise placed into forms where it dries in place.