Dynamic behaviour of an earthen material under different impact loading conditions

Luigi Fenu,Daniele Forni,Francesco Aymerich,Nicoletta Tesio,Ezio Cadoni,Luca Francesconi

doi:10.1051/epjconf/201818302014

Abstract

The dynamic behaviour of earthen materials reinforced with natural fibres is little studied although earth buildings are often built in seismic areas. In this paper the dynamic behaviour of an earthen material reinforced with hemp fibres under different impact loadings has been experimentally investigated. The dynamic response of the material in 3-point bending was investigated through an instrumented dropweight device, while the response in tension and in compression was investigated through a modified Hopkinson bar device. Typical impact response curves for tension, compression and bending impact tests have been obtained. The favourable effect of fibres in dissipating fracture energy under impact loads has been observed in all these types of test.

Highlights

Buildings in earthen materials still attract considerable interest
This study examines the improvement in the dynamic behaviour provided by the addition of hemp fibres with different weight fractions in an earthen material
Reinforcing the earthen material with fibres is a traditional practice in earth construction because highly reduces brittleness of the earthen material and increases earth buildings ductility

Summary

Introduction

Buildings in earthen materials still attract considerable interest. They are widespread in many developing countries and in rural areas, and are often of particular interest for architectural heritage [1,2,3,4,5]. The low strength and the brittle behaviour are probably the major issues for structural use of earth-based materials, for buildings and constructions likely to be subjected to seismic events [9,10,11,12,13]. For this reason vegetal fibres (especially straw) are usually used to reinforce the earthen material [14]. The results of the study show that hemp fibres improve significantly the mechanical and fracture properties of the earthen material under both static and dynamic bending. It was found that the structural properties of unreinforced and reinforced earthen materials are highly sensitive to the stress-rate, with higher strength and fracture resistance under impact loading than under static loading

Material characteristics

Sample preparation

Instrumented drop-weight impact testing machine

Results

Conclusions