Mineralization curing parameters-driven performance differentiation in granulated blast furnace slag and electric arc furnace slag binders:Unraveling the activation mechanisms of carbide slag single-activator versus Na₂SiO₃hybrid systems AITranslate

Basic Information:

DOI：

Chinese Library Classification Number:TD803[矿业工程—矿山开采];X701[环境科学与工程—环境工程]

Citation Information:

Aiming at the prominent problems of high cost of cementitious materials and low CO₂sequestration efficiency in mine filling,this study systematically explored the influence mechanism of the mineral activator carbide slag(CS)and its composite activation with Na₂SiO₃(sodium silicate,SS)on the properties of low-activity electric arc furnace slag(EAFS)and granulated blast furnace slag(GBFS)-based cementitious materials.By preparing carbon-sequestering backfill materials with CS and CS–S_Sas activators,mineralization tests were conducted under controlled CO₂curing parameters(pressure:0.2–0.4 MPa,concentration:20%–60%,curing duration:1–4 h).Comprehensive characterization via X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR),thermogravimetry-differential scanning calorimetry(TG-DSC),and scanning electron microscopy(SEM)was performed to elucidate the evolution of hydration products and microstructures.It was revealed from the experimental results that,for the CS single-activation system,the 3-day and 7-day uniaxial compressive strengths(UCS)of the cementitious materials decreased with an increasing EAFS replacement ratio.The UCS peaked at 6.81 MPa(3-day)and 10.96 MPa(7-day)when EAFS replacement was 20%(with 20%or 30%CS,respectively).However,excessive CS reduced strength due to insufficient GBFS participation.The CS–S_Ssynergistic activation system exhibited superior early-age strength(17.66 MPa at 3-day or 22.01 MPa at 7-day),confirming the dominant role of SS in early hydration.Mineralization significantly enhanced the performance of the CS single-activation system:the 3-day strength increased by 1.90–2.77 times(reaching 11.60 MPa)compared to the control group(4.20 MPa),but it weakened the CS–SS synergistic activation system.It was identified via orthogonal analysis that CO₂concentration(40%)was the primary factor influencing the 3-day strength of the CS single-activation system,followed by pressure(0.4 MPa)and curing duration(1 h).This validates that mineralization can be achieved under non-pure CO₂and non-high-pressure conditions.Microstructural analyses showed that the CS single-activation system promoted the formation of C–(A)–S–H gel and CaCO₃,whereas composite systems underwent decalcification of C–(A)–S–H gels during mineralization.This study uncovers the synergistic advantages of CS under CO₂mineralization conditions and the incompatibility between the CS–S_Ssynergistic activation system and CO₂mineralization curing,providing theoretical foundations and technical pathways for developing low-cost mine backfill materials with high CO₂sequestration capacity.