Mechanical performance of fiber-reinforced alkali activated un-calcined earth-based composites

This paper presents the results of a multi-scale study of the mechanical properties of model earth-based composites. The composites are produced by the alkali activation of in-situ clay minerals within an earth-based matrix that is reinforced with two different fibers (sisal and polypropylene). The local mechanical properties of the fibers, binder and matrix materials are characterized at the nano- and micro-scales using nano-indentation and statistical deconvolution techniques. The macro-mechanical properties are also elucidated using a combination of flexural strength testing, and resistance-curve experiments. The underlying strengthening and toughening mechanisms are explored using a combination of in-situ/ex-situ observations and micro-mechanical models. The implications of the results are then discussed for the design of strengthened and toughened earth-based composites that are reinforced with natural fibers (such as sisal) and synthetic fibers (such as polypropylene fibers).