Abstract: As an inevitable by-product of the steel industry, blast furnace slag increases rapidly with the fast growth of production. To protect the environment and creat more economic benefit, it is important to carry out theoretical studies on slag cement. It is shown that hydration reaction and the compressive strength of
concrete increase with decrease of the particle size of blast furnace slag powder. The particle size distribution of blast furnace slag has a significant impact on the mechanical strength of cement.

Key words: blast furnace slag, concrete, hydration, pH value