Laboratory scale testing of extruded earth masonry units

Abstract

There has been a resurgence in use of earth as a construction material largely driven by environmental concerns. Extruded earth masonry is a method of earth brick production that utilises existing fired brick manufacturing techniques. Extruded earth has distinct physical characteristics compared to other earthen building techniques. As industrial scale extrusion trials require large volumes of material, laboratory scale material development relies on samples prepared using alternative forming methods, such as moulding and compaction, which do not reliably reproduce the full-scale manufacturing process. The paper presents a representative method of manufacturing small scale extruded earth bricks. A suitable testing methodology is proposed, with varying curing conditions investigated. The small scale bricks are compared against equivalent large scale unfired earth bricks. The small scale bricks achieved a compressive strength of 3.39MPa and with a corrected difference compared to the full scale bricks of 0.07MPa; were found to be a reliable basis for laboratory scale investigation of material performance. The relationship that describes the effect of moisture content on strength exists for both small and large scale bricks.