Assessment of Durability of Bio-based Earth Composites

Aurélie Laborel-Préneron,Jean-Emmanuel Aubert,Paulina Faria,Camille Magniont

doi:10.21926/rpm.2102016

Abstract

Bio-based earth composites present various environmental benefits, such as usable wastes, coproducts, abundant or renewable materials, etc. Moreover, the incorporation of bioaggregates in the earth matrix allows the buildings to act as an effective carbon sink. A growing number of studies are now focusing on the mechanical and hygrothermal properties of bio-based earth building materials. However, the durability of these types of material is a major concern, and knowledge of their various aspects is essential to anticipate maintenance and sustain the performance levels. Here, the durability of compressed earth composites, valorizing discarded earth containing 3% of barley straw, hemp shiv, or rice husk, is investigated. Due to the lack of internationally recognized standards to assess the durability of earthen materials and products, we proposed some testing procedures and discussed their relevance. The addition of these three bioaggregates decreases stiffness, as estimated by ultrasound velocity, and improves the resistance to impact and erosion by water. However, water absorption under low pressure is increased, and dry abrasion resistance is decreased. Moreover, the rice husk composite presents the best compromise.

Highlights

Earth building materials are continuously being recognized for their large-scale availability, low environmental impact, and capacity to regulate indoor climate [1]
We studied three plant aggregates in this work: barley straw, hemp shiv, and rice husk (Figure 1)
Three plant aggregates were tested as the components of earth composites: barley straw, hemp shiv, and rice husk

Summary

Introduction

Earth building materials are continuously being recognized for their large-scale availability, low environmental impact, and capacity to regulate indoor climate [1] They can present major drawbacks, such as low resistance to liquid water, ductility, and significant shrinkage. These drawbacks are barriers to the spreading of earthen architecture, along with difficulty to understand and predict their long-term behavior, that is, durability [2] Some of these drawbacks can be improved partially by the addition of plant aggregates and fibers [3,4,5], while some other drawbacks, such as susceptibility to fungal growth, can occur [6]. Few of them have focused on durability [10,11,12]

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