## 1 Introduction
The steel sector prioritizes large-scale SS valorization, coinciding with urgent demands for sustainable cementitious alternatives to mitigate Portland cement's environmental footprint [17; 18]. [PERSON]'s team [19] identified threshold effects in SS replacement ratios (20-30%) for foam concrete: optimal strength gains occur through synergistic hydration and microaggregate activation, while exceeding 30% induces interfacial defects and strength loss from aggregate sedimentation and binder deficiency. This threshold behavior establishes vital processing guidelines for SS-incorporated lightweight concrete formulations. [PERSON] and [PERSON] [20] formulated compressive criteria for eco-friendly cement matching Type I Portland through a ternary binder system (8% SS, iron slag, limestone). Given SS's restricted cementitious reactivity, industrial applications typically cap its incorporation at low ratios (\(\leq\)10%) to ensure cement matrix performance. [PERSON]'s group [21] reported that SS addition under fixed W/C ratios generally decreases early-age compressive strength. At a low W/B, SS minimally impacts strength, permeability, and carbonation resistance, whereas a high W/C ratio accelerates drying shrinkage and compromises long-term strength. [PERSON]'s research [22] revealed that SS fine aggregates improve quasi-static/dynamic compressive strength and stiffness-brittleness characteristics, although the impact resistance follows a non-monotonic trend, peaking at moderate SS dosages. Ceramsite, a sustainable construction material manufactured through foaming processes in roller kilns using clay/shale/coal gangue/biosludge, exhibits superior characteristics, including lightweight structure, mechanical robustness, and thermal efficiency. Recent years have witnessed accelerated advancement and extensive utilization of ceramics in construction engineering. As demonstrated in lightweight aggregate concrete formulations where ceramicsite replaces conventional coarse aggregates, experimental data confirms an approximately 25% decrease in bulk density [23]. Ceramsite-enhanced lightweight concrete exhibits marked advantages over traditional concrete in critical metrics: thermal regulation (15-30% improvement), noise attenuation (20-25 dB reduction), service life extension (\(\geq\)50%), and seismic energy dissipation (30-45% increase) [24; 25; 26; 27; 28; 29; 30; 31]. Nevertheless, surpassing optimal ceramicsite incorporation levels (>35 vol%) can compromise the concrete matrix's structural integrity. [PERSON]'s team [32] documented non-monotonic compressive behavior in ceramsite-aerated concrete: strength enhancement (5-15% increase) at 10-25% ceramsite content, followed by degradation (20-30% loss) beyond a 30% dosage. An increasing ceramsite proportion elevates the dry density (from 800 to 1450 kg/m\({}^{3}\)) and thermal conductivity (0.18-0.35 W/m\(\cdot\)K), yet reduces the water absorption capacity (18% to 6%) [32]. [PERSON]'s research [33] revealed that shale-fly ash hybrid ceramicsite aggregates reduce drying shrinkage by 40-60% through controlled moisture release mechanisms in foam concrete matrices. The inherent microcrack formation (0.5-2 \(\upmu\)m width) during ceramsite incorporation can lead to 10-20% compressive strength reduction compared to defect-free systems. [PERSON] [34] demonstrated that cold-bonded fly ash ceramsite concrete attains 30-48 MPa compressive strength, while sintered ceramsite counterparts reach 34-54 MPa, indicating a 12-15% performance differential. In summary, utilizing construction solid waste as aggregates or cementitious materials for producing novel foam concrete still holds broad research prospects and market potential. Steel slag, as a metallurgical solid waste, possesses favorable mechanical properties. When steel slag powder is used as a cementitious material to partially replace cement, it not only reduces cement consumption but also significantly enhances specimen strength through synergistic hydration effects and microaggregate effects.