Compressive Strength of Fly ash-based Geopolymer Concrete with a Variable of Sodium Hydroxide (NaOH) Solution MolarityHerwani, Ivindra Pane, Iswandi Imran and Bambang BudionoMATEC Web Conf., 147 (2018) 01004DOI: https://doi.org/10.1051/matecconf/201814701004