High volume fly ash as substitution of fine aggregates with the proportion of 50%, 60%, and 70% to the shear strength of reinforced concrete beamsAde Lisantono, Haryanto Yoso Wigroho and Daniel Krisna MurtiMATEC Web Conf., 195 (2018) 02024DOI: https://doi.org/10.1051/matecconf/201819502024