Iqlima Nuril Amini, Meity Wulandari, Bambang Sabariman, Yogie Risdianto, Irwanda Laory, Andri Kusbiantoro, Puput Risdanareni, Martin Anda, Candra Irawan, Subaer, Verona Amelia, Januarti Jaya Ekaputri
AbstractThe variability and low reactivity of low-quality fly ash (LQFA) limit its performance as a precursor in geopolymer binders. These limitations result in slow strength development, limiting its suitability for precast applications requiring sufficient handling strength and crack resistance. This study investigates the effectiveness of polyvinyl alcohol (PVA) fiber combined with steam curing in improving the fresh and hardened properties of LQFA-based geopolymer paste. Two fly ashes with distinct chemical and physical characteristics were characterized, followed by testing of fibrous paste using LQFA incorporating 0, 0.3%, 0.6%, and 0.9% PVA by volume. The results indicate that the fly ash with higher Calcium Oxide (CaO) content and finer particle size exhibited shorter setting time, better workability, and superior compressive strength. Although the incorporation of PVA fibers slightly reduced workability, it significantly enhanced mechanical performance. The mixture with 0.6% PVA achieved the highest compressive strength of 306.3 kg/cm² at 28 days. Flexural testing revealed improved post-cracking behavior and increased toughness due to effective crack-bridging, while excessive fiber content promoted agglomeration, reducing peak flexural load. Direct tensile tests showed an increase in tensile strength up to 2.2 MPa at 0.9% PVA. Ultrasonic Pulse Velocity (UPV) results demonstrated reduced pulse velocity at higher fiber contents, indicating increased internal heterogeneity caused by fiber clustering. Overall, the findings demonstrate that properly dispersed PVA fibers can effectively compensate for the brittleness and low reactivity of LQFA, enhancing its potential use in sustainable geopolymer-based non-structural precast elements, particularly thin-walled drainage components such as U-ditch segments. © 2026 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license. http://creativecommons.org/licenses/by/4.0/
Department of Civil Engineering, Faculty of Engineering, Universitas Negeri Surabaya, Kampus UNESA Ketintang, Surabaya, 60231, Indonesia; School of Engineering, The University of Warwick, Coventry, CV4 7AL, United Kingdom; Department of Civil Engineering Technology, Faculty of Engineering Technology, Universiti Tun Hussein Onn Malaysia, Hab Pendidikan Tinggi Pagoh, KM 1, Jalan Panchor, Panchor, 84600, Malaysia; Department of Civil Engineering, Faculty of Engineering, State University of Malang, Semarang Street 5, Malang, 65145, Indonesia; Environmental Engineering, School of Engineering and Energy, College of Science, Technology, Engineering and Mathematics, Murdoch University, 90, South St, Murdoch, 6150, WA, Australia; Department of Civil Engineering, Faculty of Civil, Planning and Geo Engineering, Institut Teknologi Sepuluh Nopember, Kampus ITS Sukolilo, Surabaya, 60111, Indonesia; Material Physics Laboratory, Department of Physics, Faculty of Mathematics and Natural Sciences, Kampus UNM Parangtambung, Jl, Daeng Tata, South Sulawesi, Makassar, 90223, Indonesia; Department of Environment, PT Petrokimia Gresik, Jl. Jend Ahmad Yani, Gresik, 61119, Indonesia; Ash and Mud Resource Lab. Inc., General Research Building E202, Tokiwadai 79-5, Hodogaya-ku, Yokohama-shi, 240-8501, Japan
