The utilization of two kinds of iron slag in the production of pozzolanic cement is introduced. A series was created with
a fxed percentage of OPC (30%) and varying amounts of imported granulated blast-furnace slag (IGBFS) and air-cooled
slag (ACS) at which imported IGBFS was substituted by ACS with the mass ratios of 10, 20, and 30%. Physico-mechanical
properties and hydration parameters of the hardened pastes were examined at diferent time intervals. Furthermore, the
aggressive attack of seawater on chosen specimens was studied for up to one year of immersion. The hardened composite
cement pastes were tested in terms of weight loss, compressive strength, bulk density, total porosity, and free lime at diferent
thermally treated temperatures starting at 105 °C and ending at 800 °C for 2 h of a socking period to investigate its thermal
characteristics. XRD, IR, and DTA/TGA techniques were used to examine some chosen samples. The results revealed that the
incorporation of ACS reduces the water consistency and prolongs setting times. Compressive strengths are higher in samples
containing 10% ACS than those specimens containing 20–30 wt% and without ACS. A 7% reduction in the compressive
strength was achieved by A1 (30%OPC and 70% IGBFS), which is the lowest one over 1 year of exposure to seawater. The
incorporation of ACS at the expense of IGBFS tends to lower the strength but tends to enhance the bulk density.