en Structure-Concrete Structure- Concrete Research Paper Research Paper It was found out that the logarithmic models fit the cement–slag blend systems well. In the present study, based on the experimental results, a logarithmic model has been developed to predict the compressive strength of chemically activated high phosphorous slag content cement. Mixes of phosphorous slag (80 wt.%), Portland cement (14 wt.%) and compound chemical activator (6 wt.%) were prepared at different Blaine finenesses using a laboratory ball mill. Compressive strengths of mortar specimens cured in lime-saturated water were measured at different curing times. Mathematical model was prepared in terms of curing time and water-to-cement ratio as independent variables and compressive strength as dependent variable. The comparisons between the model reproductions and the experimentally obtained results confirm the applicability of the presented model. Phosphorous slag, Compressive strength, Water-to-cement ratio, Modeling 481 487 http://ijce.iust.ac.ir/browse.php?a_code=A-10-75-5&slc_lang=en&sid=1 A. Allahverdi ali.allahverdi@iust.ac.ir 180031947532846008067 180031947532846008067 Yes Iran University of Science and Technology M. Mahinroosta Mahinroosta2010@gmail.com 180031947532846008068 180031947532846008068 No Iran University of Science and Technology