Karakteristik dan Sifat Mekanik Mortar Self-Healing Geopolymer Berbahan Dasar Fly Ash Berbasis Hydrogel terhadap Paparan Suhu Tinggi

Abstract

The use of Portland cement in construction produces significant carbon dioxide (CO₂) emissions, so that more environmentally friendly alternative materials are needed. Fly ash-based geopolymers are a potential solution, but exposure to high temperatures can reduce their performance. This study developed a self-healing geopolymer mortar by adding hydrogel to improve resistance to high temperatures. The purpose of the study was to determine the effect of high temperatures on the compressive strength of mortar at various alkali activator molarities (6M, 8M, 10M, 12M) and its microstructural characteristics. The experimental research method involved the manufacture of 5×5×5 cm cube mortar test specimens with variations in hydrogel addition. The test specimens were cured at room temperature for 28 days, then fired at 1000°C for 4 hours and tested for compressive strength. The results showed that mortar without hydrogel with a GFA molarity of 12M achieved the highest compressive strength of 22.77 MPa. The addition of hydrogel accelerated the initial setting time but decreased the compressive strength due to increased porosity during firing. Microstructural analysis with SEM showed amorphous and reactive fly ash morphology. In conclusion, geopolymer mortar without hydrogel at 12M molarity gave the best performance against high temperature exposure, while hydrogel has the potential as a self-healing agent but needs formulation optimization to reduce porosity.