1. Center of Excellence Geopolymer and Green Technology, School of Materials Engineering, Universiti Malaysia Perlis, Perlis, Malaysia; Faculty of Engineering Technology, Universiti Malaysia Perlis, Perlis, Malaysia
2. Faculty of Engineering Technology, Universiti Malaysia Perlis, Perlis, Malaysia
3. Faculty of Engineering Technology, Universiti Malaysia Perlis, Perlis, Malaysia; Faculty of Technology, Universitas Ubudiyah Indonesia, Banda Aceh, Indonesia