Experimental Study on the Use of Iron Tailings-Based Multicomponent Solid Waste as SCMs

A considerable amount of carbon dioxide is released during the preparation of traditional Portland cement, which is not in conformity with the sustainable road. Developing supplementary cementitious material (SCMs) and reducing cement consumption are safe ways to solve this problem. Iron tailings (IOTs), a type of mining waste from the beneficiation process of iron ore concentrate, can be used as SCMs in concrete. In order to tackle the problem of low compressive performance of IOTs as SCMs in concrete, this study develops a multi-SCMs system based on IOTs. Mechanical properties and microstructure of samples with different activator contents and ratios were analyzed by compressive strength, differential thermal–thermal gravimetric analysis (DTA-TG), and scanning electron microscopy (SEM). The results show that the compressive strength of the composite gel blocks in different gel systems changed as follows: ternary SCMs system > binary SCMs system > unary SCMs system. The ternary SCMs system (IOTs: Steel slag(SS):Phosphorus slag(PS) = 1:2:2) without activator was added so that it resulted in the highest compressive strength in multi-SCMs system. With the increase in the content of activators, the compressive strength with ternary SCMs system shows a decreasing trend. It is well known from DTA-TG, as well as SEM, that NaOH and Na 2 SiO 3 have an inhibitory effect on the secondary hydration reaction and inhibit the formation of C-S-H gel.