Muralia Hustim, Purwanto, Sandri Linna Sengkey, Rita Irmawaty,. “Study of Compressive Strength and Durability of Fly Ash and Trass Based Geopolymer Mortar”. Design Engineering (November 2, 2021): 9246-9260. Accessed April 29, 2024. http://thedesignengineering.com/index.php/DE/article/view/5969.