Homogeneity and Isotropy of Compressed and Stabilized Earth Block Material: Mechanical Characterization and Statistical Analysis

Abstract

Compressed and stabilized earth block (CSEB) masonry is a locally appropriate alternative for low-rise dwellings that offers attractive affordability, sustainability, and durability features. From a designer’s perspective, the availability of standards for material characterization and design codes is essential for CSEB masonry to be accepted and adopted. However, current standards and codes are limited—this is certainly the case in North America—and largely rely on empirical and prescriptive provisions that are adapted from those for conventional masonry (e.g., fired-clay or cinder-block). Advancing standardization and codification calls for advances in the fundamental understanding of material and structural behavior as a function of constituents and manufacturing methods. For CSEBs that are customarily compacted using metallic molds and hydraulic presses, a fundamental gap lies in the understanding of whether the heterogeneity of stabilized soil mixtures, together with their manufacturing process, result in block materials that can be approximated as homogeneous and isotropic at the scale of specimens used for physicomechanical characterization. This paper reports on an investigation of a CSEB material whose constituent properties and manufacturing process are representative of those frequently encountered in North America. Homogeneity and isotropy are established based on empirical evidence from microscopic and chemical analysis, and on the statistical analysis of uniaxial compressive strength and stiffness data obtained from samples that were extracted from different areas of different source blocks, and then tested by applying loads parallel or perpendicular to the compaction direction.