<p>A mixed cement which consists mainly of ground granulated blast furnace slag having an aluminum proportion of 12-17.5 mass% and portland cement, the content of the ground granulated blast furnace slag being 10-60 mass%. The mixed cement further contains gypsum having a specific surface area of 7,000 cm<SUP>2</SUP>/g or larger in an amount of 2-4 mass% in terms of SO<SUB>3</SUB> amount. Use of this mixed cement as a raw material for concrete is effective in inhibiting the concrete from expanding even when in contact over long with soil containing a sulfate remaining therein.</p>
