Abstract: The continuous development of clean coal technology in our country has brought a large amount of industrial by-product gasification slag. From the point of view that gasification slag was used as cement mineral admixture, the dissolution characteristics of the gasification slag in different environments were determined by ICP, and its hydration activity was observed. Then the effect of gasification slag on the workability and mechanical properties of the binary composite system was studied. It is concluded that the dissolution rate of Ca²⁺ is low and the gasification slag has no self-hardening property. The dissolution rate of Si⁴⁺ and Al³⁺ increases with time, and the gasification slag has hydration activity. Alkaline and high temperature environments promote the dissolution of Si⁴⁺ and Al³⁺, indicating that the gasification slag is more likely to break chemical bonds and increases hydration activity under appropriate excitation. The morphological effect of the gasification slag improves the workability of the binary system, and the fluidity of the system with 30% and 50% (mass fraction) gasification slag increases by approximately 8.8% and 19.4%, respectively. The binary system conforms to the fluid model described by Herschel-Bulkey, and shear thinning is found. The pozzolanic reaction of low content gasification slag improves the mechanical properties of the composite cementitious system, and the 90 d compressive strength reaches 90 MPa. The high content gasification slag replaces too much cement, reduces hydration products and environmental alkalinity, the activity of the gasification slag cannot be fully excited, resulting in the increase of porosity, loose structure, and decrease of mechanical properties.

Key words: gasification slag, composite cementitious material, dissolution characteristic, workability, mechanical property