Effect Of Ion Doping On Color Performance Of White Portland Cement Clinker

Strictly controlling the content of coloring elements in the raw materials of WPC production is a necessary condition for the preparation of high-grade WPC.The natural raw materials that meet the quality requirements of WPC are facing depletion.Therefore,it is important to study and master the influence of relevant metal elements（or ions）in the raw materials on the composition and color rendering properties of WPC clinker,and to optimize the ion compatibility in the clinker to control the quality of WPC clinker and broaden the source of WPC raw materials.significance.In this paper,Rietveld-XRD,SEM-EDS,spectrophotometer and other analysis and testing methods are used to select three coloring metal ions of Fe,Cu,Cr,Mg ions commonly found in limestone,and general mineralizer F ions as Doping ions,the effects of these ions doping on the composition and color rendering properties of single minerals of clinker and WPC clinker were studied to achieve quantitative control of whiteness and color of WPC clinker.Research indicates:（1）The order of whiteness and lightness values of each single mineral is:C₃S>C₂S>C₃A>C₄AF.The doping of Cureduces the whiteness,while the doping of Fe and Cr aggravates the color cast effect of silicate minerals.Among them,the doping of Cr makes the green color cast of C₃S prominent,while the color cast effect of the doping of Cu is weak.（2）The increase of Fe₂O₃content in clinker can promote the formation of C₃S,but it will reduce the color development performance of clinker.The content of Fe₂O₃that can be tolerated by high-brightness white cement is within a certain threshold（0～0.3%）content.Within this range,the Hunter whiteness does not change significantly,but it will cause a certain color cast effect.（3）The lightness and whiteness of WPC clinker gradually decreased with the increase of ion content,but the influence of Cu ions was small,the decrease trend was obvious after the addition of Cr ions,and the yellow and green color cast effects were also more significant.The chromaticity properties of clinker doped with Fe/Cu ions and 0.1%CuO are the best.The color cast of the double-doped Fe/Cr ion clinker is weaker than that of the single-doped Cr.（4）The composite doping of CaF₂and MgO can promote the burning of W PC clinker and improve the stability of cement.When F/Mgis in the range of 1～2,the most C₃S content can be formed in the clinker.When F/M g=5,the number of R-type C₃S reaches the maximum.With the increase of F/Mgg,part of the M3 type C₃S in the clinker gradually transformed into the R type,the grain size of C₃S showed a trend of decreasing first and then increasing,and the whiteness and lightness of the clinker gradually increased.The incorporation of MgO has a certain effect on the color cast of WPC clinker.