Effect of plant aggregates on the mechanical properties of earth bricks 25 26 ABSTRACT 27A building material is mainly characterized by its mechanical performance, which 28 provides proof of its quality. However, the measurement of the compressive or 29 flexural strength of an earth-based material with plant aggregates, which is very 30 ductile, is not fully standardised. The objective of this study is to determine the 31 compressive and flexural strengths of a composite made of earth and 0%, 3% or 32 6% of barley straw, hemp shiv or corn cob. Given the manufacturing processes 33 available, cylindrical compressed specimens were studied in compression 34 whereas extruded specimens were studied in flexion. Two protocols were tested 35 for compressive strength measurements: one with direct contact between the 36 specimen and the press, and the other with reduced friction. The test with 37 reduced friction engendered a huge decrease of the stress and a slight decrease 38 of the strain. For both compressive and flexural strengths, the specimens made 39 of earth alone were the most resistant, followed by composites containing straw. 40