Rumiyanti L, Listiani L, Damayanti T. OPTIMIZATION OF THE USE OF FLY ASH AS AN ADDITIVE PORTLAND COMPOSITE CEMENT (PCC). SPEKTRA [Internet]. 2019Aug.31 [cited 2026Apr.8];4(2):61 -72. Available from: http://103.8.12.212:33180/unj/index.php/spektra/article/view/10035