Determining Material Characteristics of “Rammed Earth” Using Non Destructive Test Methods for Structural Design

Abstract

Rammed earth is an ancient construction material which has recently regained the attention of the stakeholders involved in the maintenance of older buildings and design of new buildings according to the rules of modern sustainable architecture. The homogeneity and stability of the construction are enhanced through mixing with an additive and compaction of the mix inside a removable formwork. Control or assessment of the material properties is essential for the accurate design or assessment of a structure, in particular for cases of poor fundamental understanding of the structural behavior, like rammed earth. Moreover, the obvious need for limiting pre-assessment intervention, especially for historic rammed earth buildings, has given rise to the importance of non- destructive testing for the determination of material features. This thesis proposes to treat cement-stabilized rammed earth similarly to concrete or natural rock for determining its compressive strength and quality through non-destructive testing techniques. The tested specimens were fabricated by adding industrial waste additives such as Fly ash & Metakaolin with cement-stabilized soil. Then, three rounds of non-destructive evaluations using the Rebound Hammer Test and the Ultra Sonic Pulse Velocity Test were performed on specimens exposed to wetting-drying cycles and ambient conditions in a time lapse of one month and one year for the wall to evaluate the effect of environmental conditions and time on the material characteristics. Compression testing of cylinders up to failure was also performed to assess the compressive strength of rammed earth and to benchmark the results of non-destructive tests. Moreover, different mix designs were selected to evaluate the impact of adding industrial waste additives in the material characteristic.