Cracking due to the restrained shrinkage stress has been frequently observed at early age in concrete structures. Early-age deterioration of concrete due to cracking and higher maintenance cost for poor durability cause serious troubles to concrete structures. Steel slag includes a certain scale mineral such as C2S and C3S, and can be applied in cement and concrete as mineral admixtures. Two tests are outlined to quantify the behaviour of concrete under restrained shrinkage using plate and ring specimens. The results show that mineral admixtures can be used to reduce cracking in concrete. The risk of cracking can be estimated for steel slag concrete, so that it will improve the durability of concrete structures.