Compressive Test and Microstructure Analysis of the Coconut Fiber Ash-based Geopolymer Binder

Abstract

This watchfulness goal is to define the compressive test value and microstructure of a geopolymer binder made from coconut fiber ash (CFA). CFA comes from the combustion of coconut fibers in the tile-making industry in Tabanan, Bali. This waste is processed into CFA, which consists of 8.24% silicon dioxide, 70.6% potassium oxide, 14.1% chlorine, 2.3% diphosphate pentoxide, and 2.25% iron dioxide. CFA is then used as a crude material for the manufacture of geopolymer binders. The mixture's proportion consisted of three groups of variations: the ratio of precursors and activators, P/A: 70%:30%; 75%:25%; and 80%:20%. In the experiment, Na₂SiO₃ and a 14 M molar concentration of NaOH were combined in weight ratios of 1:1, 1.5:1, and 2:1. These are both alkaline activators. The sample was shaped into 50-mm cubes, dried in an 80℃ heater for 24 hours, and then tested at 7 and 28 days. The ASTM-C39 standard was used for the compression test, while the microstructural analysis used X-RD and SEM-EDX. The results showed that coconut fiber ash precursors could be used to generate a geopolymer binder with a compressive value of 4.67 MPa and 6.24 MPa on the 7^th and 28^th days of testing, respectively. The microstructure of the solid sample, which was associated with the rise in compressive value, was characterized using scanning electron microscopy. Using 80% CFA gave the best results.