*Article* **Mechanical Properties of Fly Ash-Based Geopolymer Concrete Incorporation Nylon66 Fiber**

**Muhd Hafizuddin Yazid 1,2, Meor Ahmad Faris 1,3, Mohd Mustafa Al Bakri Abdullah 1,2,\*, Muhammad Shazril I. Ibrahim <sup>3</sup> , Rafiza Abdul Razak <sup>1</sup> , Dumitru Doru Burduhos Nergis 4,\* , Diana Petronela Burduhos Nergis <sup>4</sup> , Omrane Benjeddou <sup>5</sup> and Khanh-Son Nguyen <sup>6</sup>**


**Abstract:** This study was carried out to investigate the effect of the diamond-shaped Interlocking Chain Plastic Bead (ICPB) on fiber-reinforced fly ash-based geopolymer concrete. In this study, geopolymer concrete was produced using fly ash, NaOH, silicate, aggregate, and nylon66 fibers. Characterization of fly ash-based geopolymers (FGP) and fly ash-based geopolymer concrete (FRGPC) included chemical composition via XRF, functional group analysis via FTIR, compressive strength determination, flexural strength, density, slump test, and water absorption. The percentage of fiber volume added to FRGPC and FGP varied from 0% to 0.5%, and 1.5% to 2.0%. From the results obtained, it was found that ICBP fiber led to a negative result for FGP at 28 days but showed a better performance in FRGPC reinforced fiber at 28 and 90 days compared to plain geopolymer concrete. Meanwhile, NFRPGC showed that the optimum result was obtained with 0.5% of fiber addition due to the compressive strength performance at 28 days and 90 days, which were 67.7 MPa and 970.13 MPa, respectively. Similar results were observed for flexural strength, where 0.5% fiber addition resulted in the highest strength at 28 and 90 days (4.43 MPa and 4.99 MPa, respectively), and the strength performance began to decline after 0.5% fiber addition. According to the results of the slump test, an increase in fiber addition decreases the workability of geopolymer concrete. Density and water absorption, however, increase proportionally with the amount of fiber added. Therefore, diamond-shaped ICPB fiber in geopolymer concrete exhibits superior compressive and flexural strength.

**Keywords:** geopolymers; geopolymer concrete; polymer fiber reinforced geopolymers; interfacial bonding
