Hempcrete is a bio-composite made of the inner woody core of the hemp plant mixed with a lime-based binder. The hemp core or “Shiv” has a high silica content which allows it to bind well with lime. This property is unique to hemp among all natural fibers. The result is a lightweight cementitious insulating material weighing about a seventh or an eighth of the weight of concrete.
Fully cured hempcrete blocks float in a bucket of water. It is not used as a structural element, only as insulating infill between the frame members though it does tend to reduce racking. All loads are carried by internal framing. Wood stud framing is most common making it suitable for low-rise construction. Hempcrete buildings ten stories high have been built in Europe.
Hemp has always been a cash crop. Fuel may be the most important product you can get from hemp for our growing energy needs, but there are literally thousands of different products you can make from hemp. From clothing, to makeup, to biodegradable plastics, it’s pretty much a miracle plant. It has 4x the yield of tobacco, is incredibly resilient to changes in environment and it grows very quickly. I would argue that hemp would be a staple in any sustainable society. It’s really a shame that it’s illegal in the US.