Bond Characteristics of Earth Block Masonry

Abstract

Earth block construction offers a low energy alternative to conventional low-rise building materials such as clay fired masonry units, concrete, processed timber, and steel framed construction. Used to some extent in areas such as New Mexico, further development of the technology has been hampered somewhat by very limited understanding of material performance. In this paper, work undertaken to study the flexural bond strength characteristics in pressed earth block masonry is summarized. Cement stabilized pressed earth blocks were fabricated using a manual press and masonry piers were built using both cement:lime:sand and soil:cement mortars. Flexural strengths were determined using the bond wrench method. Bond strength is shown to be a function of both block and mortar strength, as well as block moisture content during construction, and mortar clay content. Bond strengths decreased significantly with saturation of the masonry but showed litle development beyond 1 day after construction. Characteristic bond strengths in pressed earth masonry are typically much less than values generally assumed in conventional masonry. In conclusion the paper outlines recommendations for mortar usage with pressed earth blocks.