煤制天然气残渣-水泥复合胶凝材料流变与力学性能

Rheological and Mechanical Properties of Coal-Based Synthetic Natural Gas Slag-Cement Composite Cementitious Materials

以煤制天然气残渣(CSNGS)为辅助胶凝材料,采用旋转流变仪、抗折与抗压试验、X射线衍射仪(XRD)、扫描电镜-能谱仪(SEM-EDS)、傅里叶变换红外光谱(FTIR)、热重分析(TG)等测试技术及方法,系统研究CSNGS对水泥复合胶凝材料流变性能、力学性能及微观结构的影响规律和作用机理.结果表明:掺入适量CSNGS可改善复合胶凝材料净浆的流变性能,当CSNGS掺量为10.0%时,净浆的屈服应力和塑性黏度分别降低27.2%和35.0%;掺入CSNGS有助于提升复合胶凝材料砂浆的抗折强度,当CSNGS掺量为20.0%时,复合胶凝材料砂浆28 d抗折强度为8.9 MPa,较水泥砂浆提高13.8%;当CSNG掺量为0%~30.0%时,复合胶凝材料砂浆28 d抗压强度可达水泥砂浆的88%以上.掺入CSNGS后反应产物中的凝胶和Ca(OH)_(2)含量减少,凝胶中n(Ca)/n(Al+Si)、n(Ca)/n(Si)及n(Si)/n(Al)降低,钙矾石(AFt)含量增加,反应产物中有水化硅铝酸钙(C-A-S-H)凝胶生成.

Coal‑based synthetic natural gas slag(CSNGS)was used as supplementary cementitious material,and the influence rule and mechanism of incorporating CSNGS on the rheological properties,mechanical properties and microstructure of cement composite cementitious materials were systematically investigated using rotational rheometer,flexural and compressive tests,X‑ray diffraction(XRD),scanning electron microscope‑energy dispersive spectrometer(SEM‑EDS),Fourier transform infrared spectroscopy(FTIR),and thermogravimetric analysis(TG).The results show that the rheological properties of composite cementitious materials can be improved by mixing appropriate amount of CSNGS,and the yield stress and plastic viscosity of the slurry can be reduced by 27.2%and 35.0%respectively when the CSNGS content is 10.0%.The incorporation of CSNGS helps to improve the flexural strength of the composite cementitious material mortar,The 28 d flexural strength was 8.9 MPa when the CSNGS content is 20.0%,representing an increase of 13.8%compared with that of the cement mortar.In addition,the 28 d compressive strength of composite cementitious material mortar can reach more than 88%of cement mortar when CSNGS is mixed in 0%-30.0%.The results also show that with the incorporation of CSNGS,the gels and Ca(OH)_(2) content decrease,n(Ca)/n(Al+Si),n(Ca)/n(Si),and n(Si)/n(Al)in the gels decreases,the content of ettringite(AFt)increases,and calcium silicaluminate hydrates(C‑A‑S‑H)are generated in the reaction products.