Mechanical characterization and durability of earth blocks

Abstract

With the growing awareness of environmental issues, raw earth construction in its various forms is experiencing a renewed interest. In fact, earth is a natural material that limits energy consumption and plays an important role in terms of humidity and temperature regulation. The demand for bio-based building materials and the addition of plant aggregates on earth building bricks is also increasing. This study focuses on the characterization of three unfired commercialized earth adobe bricks with different percentage of plant aggregates. The characterization of the constituents of the different adobe bricks has been first realized by conducting wet sieving tests, sedimentation, Atterberg limit and density tests. The performances of adobe bricks were then investigated and compared in terms of mechanical properties and durability considering freezing-thawing cycles and dry abrasion. The compressive strength is an important property but presents significant variations due to several influencing factors like source, proportion of constituent materials, curing condition, workmanship, in addition to testing procedure. Several specimens have been tested to quantify the compressive strength variability. In addition, as no consensus on the test design and limited data exists on the influence of specimen’s geometry and correlation between testing procedures and mechanical properties, a campaign of unconfined compressive tests has been conducted where several parameters have been varied such as specimen orientation and use of mortar or not. The tensile strength has been also measured with the indirect tensile test method. The effect of freezing thawing cycles was evaluated by subjecting the bricks to unconfined compressive tests after 3, 6, 9 and 12 freezing-thawing cycles. The results show a significant effect of the testing procedure on the compressive strength values. In addition, a decrease in the mechanical properties has been observed for adobe bricks exposed to freezing-thawing cycles.