Environmental aging effects on mechanical behavior of an hemp based biocomposite material for structural strengthening

Abstract

Biocomposites are innovative materials usually made of natural fibers embedded in a natural matrix. The mechanical behavior of such materials when exposed to the environmental agents (i.e. UV radiations, high/low temperature, variable humidity conditions) is a crucial issue. This paper is aimed to investigate an hemp based biocomposite for structural strengthening, addressing a gap in the existing literature concerning the mechanical characterization of the composite constituents (i.e. hemp ropes and natural matrices) under accelerated weathering conditions. In particular, this research involves the mechanical behavior assessment of hemp ropes, four distinct types of matrices (i.e. two organic binder based matrices and two mortar based matrices) and the hemp/matrix interface. Tensile tests, three point bending tests, uniaxial compression tests and pull-out tests are carried out to characterize these components. To simulate accelerated weathering, samples of the biocomposite constituents are subjected to cycles of hygrothermal stress and UV radiation using an accelerated weathering testing apparatus. Subsequently, experimental mechanical tests are performed on the aged biocomposite components, and their mechanical properties are assessed and compared to those of the non-aged materials. The results reveal that aging leads to a significant reduction in the mechanical properties of the hemp ropes, and varying effects on the mechanical properties of matrices depending on their nature (organic binder-based or mortar-based matrices).