Durability Behavior of Banana Fiber-reinforced Natural Pozzolan Geopolymer

This research investigates the durability of waste banana fiber (BF) reinforced Earth of Datça (ED)-based geopolymer (EDBG) mortar under consecutive cycles of freeze-thaw, wetting-drying, and sulfate attack tests. ED is the volcanic tuff of the Datça Peninsula in Türkiye and was utilized as an aluminosilicate source, while sodium silicate (SS) and potassium hydroxide (KOH) solutions were used for alkaline activation. BF with a 20-mm length was added to the geopolymer mortar in the contents of 0.5, 1.0, and 1.5%. Mortars were cured at 70°C and 95±5% RH for 24h, followed by ambient air curing at 20 °C and 55±5% RH for 28 days. In parallel with the increase in the fiber content added to the geopolymer (EDG) mortar, there was a slight decrease in compressive strengths but a significant increase in flexural strengths, as expected. This trend was also observed after all aging tests except after the sodium sulfate (Na2SO4) attack. With the 1.5% BF inclusion, the gain in compressive strength, flexural strength and weight was 27.31%, 12.79%, and 1.58% respectively, which might be due to the crystallization of the absorbed salts inside the structure. Among the aging tests, although freeze-thaw has the most deteriorating effect on both EDG and EDBG mortars, the utilization of fiber decreased the damage to the material, and the integrity of the material was maintained. The behavior of the material under the effect of wetting-drying can be defined as “0-specimen intact.” Therefore, it was proven that the use of banana fiber enhanced the durability of EDBG mortars under the aforementioned aging tests, and the building material produced within this experimental study can be used safely.