In recent years, the need for a concrete of superior durability and moreeconomic than ordinary concretes is considered one of the most interestingworks for many investigators. This purpose can be accompalished by the partialreplacement of cement by the grounded slag into the concrete mix.The present work aimed at determining the effects of replacement of35% and 65% by weight of ordinary protland cement by the grounded slag oftwo types, water quenched and air cooled on the control strength properties at28 days and the durability of concrete. The control strength properties were thecompressive strength, the tensile splitting strength, flexural strength, bondstrength and the modulus of elasticity. The durability of slag concrete wasmeasured by the 6 months compressive strength and the corrosion activity ofsteel embedded in slag concrete, exposed to chlorides solution, sulphatessolution and dual solution of chlorides and sulphates as well as water as areferrence. The corrosion tests were extended to study the effect of varying thecover to reinforcement from 1 cm to 5 cm. The salt concentration were 6%, 6%and 12% respectively, and the cement content were 300, 350 and 450 kg/m-’.Similar hardend concrete tests were made for the Ordinary Protland Cement,Sulphate Resisting Cement and the Blast Furnace Slag Cement in order tocompare their results with those of slag concrete.It was found that, the control strength properties of slag concretedecreases as the slag % increases. Also, these control strength properties arelower than the Ordinary Protland Cement concrete, Sulphate Resisting Cementconcrete while it increases over the Blast Furnace Slag Cement concrete at 35%water quenched slag. The compressive strength of slag concrete exposed tocycles of chloride and cured in water decreases as the slag % increase while nosignificant changes in compresive strength of slag concrete in sulphate and inthe dual solution occured at mix of higher cement content. The compressive