硼、钠复合掺杂对贝利特-硫铝酸钙水泥性能及微观结构的影响

Effect of Combined Addition of Boron and Sodium on Property and Micro-structure of Beliet-sulphoaluminate Cement

采用粘土、铝矾土、碳酸钙为主要原料制备以贝利特(C_2S)、硫铝酸钙和铁铝酸钙为主导矿物的低碳排放水泥熟料(BCSAF),并通过硼(B)和钠(Na)复合掺杂对C_2S矿物进行活化。将熟料与无水石膏按比例混合后制备水泥,研究复合掺杂对水泥净浆强度及微观结构的影响。采用X射线衍射全谱拟合定量相分析法、红外光谱、扫描电子显微镜、X射线能谱分析等测试方法表征熟料及水泥水化浆体组成与结构。研究结果表明,一定掺量的B和Na复合掺杂制备BCSAF水泥熟料可在常温下稳定α′-C_2S或更高活性的C_2S,减少熟料中β-C_2S含量,从而实现C_2S矿物的活化,提高BCSAF水泥熟料早期水化活性,显著提高水泥浆体抗压强度。

Belite-calcium sulphoaluminate-ferrite （BCSAF） cement clinker with lower CO2-emission was prepared from clay, bauxite and calcium carbonate. During the firing process, boron （B） and sodium （Na） were combinedly doped to make the belite （C2S） more reactive. By mixing the BCSAF clinker with proper amount of anhydrite, BCSAF cement was prepared. Then the effects that B and Na have on the macro-property （compressive strengths development） and micro-structure of cement paste were investigated. Rietveld quantitative phase analysis based on the X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray energy dispersive spectrometer were utilized to study the structure and composition of the cement clinkers and hydrated paste. Results figure out that a proper addition of B and Na helps to stabilize whether α′-C2S or other C2S structure with even higher activity at room temperature, thus reducing the β-C2S proportion. By the combined addition of B and Na, the C2 S mineral in BCSAF clinker is activated, so the early-age compressive strength of the cement paste is improved.