Non-Destructive Techniques for Characterising Earthen Structures

Abstract

Earthen architecture is one of the most relevant building technologies among heritage structures. However, mechanical properties are commonly obtained from destructive tests. To contribute at changing this trend, two non-destructive mechanical techniques (ultrasound and modal analysis) are studied to determine their ability at characterizing earthen materials and their possible correlation. To achieve these purposes, twenty cubic-shaped earthen specimens were produced for testing the capability of ultrasound transmission method to control moisture content and its evolution during drying process at different environments. Additionally, a real-scale rammed earth wall was built to assess the feasibility of using ultrasound technique to determine elastic dynamic Young modulus. This analysis was validated by indirect comparison with experimental modal analysis test results. The most important findings are that the relationship between moisture content and ultrasound transmission speed is linear. This information is useful to control the drying process of earthen materials and to control the moisture content distribution on larger in-service structures. Finally, numerical simulation using ultrasound transmission data as input information allow to predict the vibrational response of the tested wall with an error around 3%.

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