Experimental investigation on the mechanical performance of starch–hemp composite materials

• This investigation shows the mechanical performance of starch–hemp composite materials.
• The failure of the starch–hemp concrete is due to the great displacement.
• The compressive strength of the starch–hemp concrete depends lightly on the material density.
• The choice of the binder is based on both the dynamic viscosity and the surface tension.
• The cartographies show that the gradient of the strain is neither homogeneous nor regular.

An experimental investigation was conducted in order to study the mechanical performance of starch–hemp composite materials. The starch–hemp composite material is 100% natural fibers and a durable material. The optimization of the binder solution has been based on the dynamical viscosity and the surface tension. The starch–hemp composite material specimens with five hemp/starch ratios, 6, 8, 10, 12 and 14, were manufactured by using the optimal binder. The density of the specimen decreases rapidly during the drying process. The duration of the drying time is between 30 and 40 days. The density value is more lightweight than that of the lime hemp concrete. The experimental results show that the tensile strength varies from 0.03 to 0.08 MPa, the elasticity modulus varies from 1.47 to 2.16 MPa and the Poisson ratio varies from 0.08 to 0.12 when the hemp/starch ratio goes from 6 to 14. This type of natural fibers composite material shows a special property, great displacement. The appearance and propagation of the crack were shown and discussed in this paper.