Projection formed and precast hemp-lime: better by design?
Projection forming and off-site pre-casting of hemp-lime panels are alternatives to traditional insitu casting that can offer several production benefits: minimised on-site time, improved quality assurance and lower drying times. The direction of compacting force applied with these methods is perpendicular to that of traditional on-site cast material and, in the case of projection formed, applied by different means. As a result the internal structure of the material will be aligned and shaped differently with consequent implications for the physical properties that must also be considered when selecting a method of production. This paper reports on the mechanical and thermal properties of hemp-lime produced by projection and by casting in two directions: vertical as per in-situ casting and horizontal as per pre-casting. The internal structure of the material in each case was assessed through image analysis and used to explain the measured differences in properties. The results indicate the importance of the orientated internal structure in determining the performance of this material and show that horizontally precast manufacture can provide inherent performance improvements over traditionally cast material in addition to the logistical benefits while projection forming may allow for thinner wall sections.