Risk of damage and desiccation cracking of construction materials based on raw earth

Ahmad El Hajjar,Said Taibi,Joanna Eid,Tariq Ouahbi,F Hage Chehade

doi:10.1051/matecconf/201928101018

Abstract

Nowadays, structures are mainly constructed using natural aggregates as sand and gravels. In the future, we would increasingly have to consider replacing them by more abundant and ecological natural materials such as raw earth. However, despite its many qualities (low gray energy, thermal and hygrometric isolation), this eco-material has some defects: cracking by desiccation. The later prevent its widespread diffusion. This study aims to understand the mechanisms of appearance and propagation of cracks in order to try to either prevent or repair it. To carry out this study, digital image correlation technique is used. It consists in performing free desiccation tests to follow the initiation and propagation of cracks, from the beginning of homogeneous strain until the appearance of discontinuity, in order to determine the strains tensor in the massif. In order to understand the origin of cracking, desiccation is studied for different boundary conditions and according to different intrinsic characteristics of the material.

Highlights

Raw earth presents an alternative as a non-energy consuming building material to deal with climatic and environmental issues
Boundary conditions influence the cracking of a clay, and the intrinsic characteristics of the material have a greater influence on its behavior
The digital image correlation allows us to identify the types of stress in the material

Summary

Introduction

Raw earth presents an alternative as a non-energy consuming building material to deal with climatic and environmental issues. Despite these advantages, the use of this construction material remains somewhat limited due to harmful desiccation shrinkage, in some drought areas. Cracking is mainly related to the presence of fine particles in the soil granulometry. These particles have a sensitivity to water, which results in major volume changes during their dehydration [1]. The size of clay particles depends on the variation in soil suction [3]

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