Preparation and application of the cement-free steel slag cementitious material

• A new kind of cement-free steel slag cementitious material is developed.
• The performances of the cementitious material are analyzed.
• A dense structure can be obtained in the adequate hydration reactions.
• The cementitious material can be used in the practical engineering.

In order to utilize the steel slag effectively, the steel slag, compound agent, fine sand, gravel and admixture are used to prepare cement-free steel slag cementitious material. The compressive strength of the mortar can reach 70 MPa. The performance tests are conducted on the C50 grade of the material. The experimental results indicate that the relative dynamic modulus of elasticity maintains at 66% and the mass loss is 1.1% at 300 cycles, so the frost resistant grade of the material is F300. The average carbonation depth is 0.3 mm, which can be regarded as no carbonized. In addition, the passed charge of the cementitious material slice for 6 h is less than 1000 C. The microstructure of the material taken from the practical engineering project is analyzed by SEM and EPMA. It is shown that the hydration reactions of the steel slag, composite agent and admixture are mutually promoted. The acicular sulphoaluminate hydrate and the villous flocculent calcium silicate sol are intertwined and linked closely with the interface of steel slag and hydrate.