Xuehong Ren;Wensheng Zhang;Jiayuan Ye;
<正>The simultaneous presence of many impurity elements affects alite through the mutual interactions of these ions,which is significantly deviated from the individual effect of each ion.In this study the effect of different kinds of combinations of the seven typical foreign ions such as Na,Mg2,etc.on the structure and reactivity of alite was studied by X-ray powder diffraction with the Rietveld method thermoluminescence,and isothermal calorimetry.Mi-type alite is stabilized with normal concentrations of the seven or six kinds of foreign ions in combination,except that the absence of either Mg2 or Al~3 results in the stabilization of T3-type alite.The overall activity of alite is dramatically increased,but the medium-term hydration reaction is retarded and the maximal thermal power is lowered Among various combinations of foreign ions, heterovalent ion replacement has the most significant influence both on the thermoluminescence and hydration behavior of alite due to the complex extrinsic defects resulting from ionic substitutions.It is revealed by thermoluminescence that the hydration reactivity,as represented by that of cumulative heat released,is proportional to the original TL intensity during the period of hydration in which the rate is controlled by nucleation and growth,but not subsequently,when it is controlled by diffusion.The extra energy stored as electrons trapped on metastable levels are believed to account for this interesting phenomenon. Originality The crystal structure and properties of alite can deviate from pure C_3S significantly.In this study the effect of different kinds of combinations of the seven typical foreign ions such as Na~-,Mg~(2-),etc.on the structure and reactivity ofalite was studied Interestingly, the hydration reactivity of alite,represented by cumulative heat released,was found to be proportional to its original thermoluminescence intensity during the thermodynamically driven period.The results obtained provide new insights into the influence mechanism of various impurities on the hydration of C_3S and help to understand the basic mechanisms of hydration.
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