Bio-Building Materials for Load-Bearing Applications: Conceptual Development of Reinforced Plastered Straw Bale Composite Sandwich Walls

Abstract

This paper presents a conceptual development of plastered straw bale composite sandwich wall systems for load-bearing applications. Straw bales are environmentally friendly and may be an alternative to conventional building materials such as masonry blocks for low-rise buildings. An experimental program is conducted to examine the feasibility of the composite system: material testing with three types of plaster materials and structural testing using seven prototype sandwich walls. Test parameters include the effect of reinforcing materials on the behavior of plaster skins and the type of reinforcement such as dense and coarse grid wire-meshes and nonmetallic glass fiber reinforced polymer (GFRP) reinforcing bars. The composite system significantly improves the load-bearing capacity of a straw bale, particularly noticeable when the coarse mesh and GFRP bars are used. The wire-meshes restrain the lateral displacement of the plaster skins and preclude the volumetric expansion of the sandwich walls subjected to axial compression. The test specimens fail by plaster crushing, local buckling, or skin collapse. The specimen with the coarse mesh is recommendable for multistacking applications of straw bale walls, given that such a combination provides low accumulated compliance and high energy absorption capacity when compared with other specimens.