Highly Pseudo Ductile Metakaolin Based Engineered Geopolymer Composites Using Low UHMWPE Fiber Content

The objective of this study was to investigate the effect of fine aggregate type (i.e., natural river sand and manufactured microsilica sand) and ultra-high-molecular-weight polyethylene (UHMWPE) fiber length (i.e., short and long) on the mechanical properties of metakaolin (MK) based Engineered Geopolymer Composites (EGCs) with 0.8 vol.% fiber cured at room temperature. EGCs produced were evaluated by compressive strength test and uniaxial tensile test. Experimental results showed that the compressive strength of the EGCs exceeded that of conventional concrete by -44-47%, while exhibiting -19-22% lower densities. However, the compressive strength was not significantly affected by the different types of sand or fibers evaluated. On the other hand, the tensile properties of the EGCs were significantly affected by the type of sand used. The use of natural river sand (RS) in specimens using long UHMWPE fiber, produced a dramatic increase in the tensile strain capacity (i.e., 129%) and a reduction in the tensile strength (i.e., 41%) in contrast to specimens manufactured using microsilica sand (MS). Nevertheless, the different types of fiber evaluated did not produce a substantial effect in the tensile properties of the composites. Notably, the EGC material using natural river sand and long UHMWPE fiber at 0.8 vol.%, presented an exceptional tensile strain capacity of 8.6%, which is comparable to that of some metals. It was concluded that metakaolin-based geopolymers matrices with UHMWPE fibers are highly promising for the manufacture of EGC materials.