International Science and Technology Journal

In this experimental study, blast furnace slag supplied from Iron and Steel Company in Misurata was used in the manufacturing of cement mortar. The pre-crashed slag was milled for periods of time ranging from 1 to 5 hours, and it was added as a partial cement replacement consisting of mortar and cement paste for each period of grinding time at a percentage of 10%, 30%, 40%. This study included testing the physical characteristics of the cement paste in its dry and wet states. In addition, the compressive strength test of the cement mortar containing different percentages of slag powder milled at different times was carried out after 3, 7, and 28 days. The results of the study revealed that the increase in grinding time is accompanied by an increase in the surface area, initial and final setting times, soundness, and a decrease in loss on ignition. The results also showed that the increase in the fineness of the slag powder with grinding is accompanied by an increase in the compressive strength. At the early ages, with the increase in the percentage of slag powder, the compressive strength was lower, but at the later age (28 days), the compressive strength of the mortar containing 10% of slag powder at a grinding time of 3.5 hours gave a higher compressive strength than the standard cement mortar. It was observed that the mortar containing 40% slag powder had a compressive strength of 27.2 MPa, which was considered acceptable in terms of structural applications. Keywords: Blast furnace slag, Mortar and cement paste, Physical characteristics, Compressive strength.