Luang, E. et al. 2026. Concrete Quality Design F’C 21 MPa Using SNI 7656:2012 Method Using Local Materials (C Ibu Selatan Quarry). JURNAL BIOSAINSTEK. 8, 2 (Jul. 2026), 97–104. DOI:https://doi.org/10.52046/biosainstek.v8i2.2789.