Production of mortar with calcined alum sludge as partial cement replacement Ai Wei Wong, Hoong Yuin Chew, Mohammed J. K. Bashir, Majed A. A. Aldahdooh and Choon Aun Ng E3S Web Conf., 603 (2025) 02008 Published online: 15 January 2025 DOI: 10.1051/e3sconf/202560302008