Analisis Kuat Tekan dan Durabilitas Mortar Geopolimer Self-Healing terhadap Perendaman Asam Sulfat (H₂SO₄) 5% dengan Variasi Molaritas

Abstract

The rapid development of infrastructure in Indonesia requires repair materials with high resistance to aggressive environments. Conventional cement-based materials are known to be vulnerable to deterioration when exposed to sulfuric acid solution (H₂SO₄) 5%, thus demanding more sustainable alternatives. This study investigates self-healing geopolymer mortar based on fly ash with and without hydrogel addition, using various NaOH molarities (6 M, 8 M, 10 M, and 12 M). Fly ash was utilized as a cement substitute, while hydrogel served as a self-healing agent capable of storing water and repairing microcracks. Cube specimens measuring 5×5×5 cm were tested to evaluate compressive strength, durability, and microstructural characteristics using the Scanning Electron Microscope (SEM) method after immersion in 5% H₂SO₄ solution for 28 days. The results showed that geopolymer mortar with 12 M NaOH without hydrogel (GFA 12 M) achieved the highest compressive strength of 14.59 MPa, while the addition of hydrogel demonstrated optimal performance at GFAH 10 M with a compressive strength of 13.19 MPa. Hydrogel addition enhanced durability at medium molarities but reduced strength at lower molarities. SEM analysis of GFA 12 M revealed a dense and homogeneous microstructure with tightly distributed particles and alkali- activated binding layers covering the fly ash particles. This condition reduced voids and microcracks, strengthened the internal matrix, and improved resistance against acid attack. Overall, geopolymer mortar exhibited better durability compared to conventional mortar and has strong potential as an eco-friendly alternative material for the repair of cement-based structures.