Effect of polypropylene fiber on workability and strength of fly ash-based geopolymer mortar

Abstract

Geopolymers do not require Portland cement as a binder; hence, the binder is replaced by a material containing high SiO2 and Al2O3 reacted with an alkaline activator (NaOH and Na2SiO3). In addition, mortar or concrete is highly susceptible to cracking, requiring the addition of polypropylene fiber (PPF). This research belongs to an experimental study examining the addition of PPF with percentages from 0%, 0.25%, 0.5%, 0.75%, and 1% by utilizing coal fly ash (FA) as a precursor. This study also added a superplasticizer (SP) and extra water (EW) to maintain the flowability. The tests were carried out on the workability, strengths, and microstructure of geopolymer mortar. Workability obtained values of 140 - 220 mm. Furthermore, the highest compressive strength of 73.3 MPa and flexural strength of 9.92 MPa were identified in the geopolymer mortar with the addition of 0.5% PPF. In addition, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) tests were applied to investigate the geopolymer microstructure.