Abstract
In this study, the influence of steel slag (SS) content on the strength of the cementitious materials was investigated. The quaternary active cementitious material (CaO-SiO2-Al2O3-SO3) was prepared using various proportions of steel slag (SS), granulated blast furnace slag (BFS), and desulfurized gypsum (DG). The mechanism of synergistic excitation hydration of the cementitious materials was examined using various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). The strength of the mortar test block was initially increased and decreased later with the increase of the SS content. Mortar test block with 20% steel slag, 65% granulated blast furnace slag, and 15% desulfurized gypsum with 0.35 water-binder ratio showed the highest compressive strength of 57.3 MPa on 28 days. The free calcium oxide (f-CaO) in the SS reacted with water and produced calcium hydroxide (Ca(OH)2) which created an alkaline environment. Under the alkaline environment, the alkali-activated reaction occurred with BFS. In the early stage of hydration reaction, calcium silicate hydrate (C-S-H) gel and fibrous hydration product ettringite (AFt) crystals were formed, which provided early strength to the cementitious materials. As the hydration reaction progressed, the interlocked growth of C-S-H gel and AFt crystals continued and promoted the increase of the strength of the cementitious system.
Highlights
Solid waste refers to the garbage and discarded material resulting from commercial, industrial, and community activities (Chen et al, 2010)
The ideal ratio to prepare cementitious material was in Group D with a steel slag content of 20% (Figure 2; Table 2)
At steel slag content of 20%, the highest flexural (9.64 MPa) and compressive (57.26 MPa) strengths were observed in the test block aged for 28 days (Figure 2)
Summary
Solid waste refers to the garbage and discarded material resulting from commercial, industrial, and community activities (Chen et al, 2010). Bulk solid waste is a key area in the field of comprehensive utilization of resources due to its large quantity, wide range, adverse environmental impact, and broad utilization prospects (S Yüksel, 2018). The generation of smelting slag has been substantially increased over the last few decades in China due to the rapid development in iron and steel industries (Li, 2020). The smelting slag accumulated on soil occupies a large area of land and form fine dust when exposed to air, thereby seriously impact on the local environment. Increasing attention has been paid to proper disposal and resource utilization of smelting slag generated from the iron and steel industries.
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