Managing trace elements in Portland cement - Part II: Comparison of two methods to incorporate Zn in a cement
Managing trace elements in Portland cement - Part II: Comparison of two methods to incorporate Zn in a cement
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DOI：
10.1016/j.cemconcomp.2011.03.008
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发表时间：
2011-07-01
影响因子：
10.5
通讯作者：
Damidot, D.
中科院分区：
文献类型：
--
作者：
Gineys, N.;Aouad, G.;Damidot, D.
本研究比较了两种固定相同锌量水泥浆体的方法。在第一种方法中。在熟化之前，锌被引入原料中，而在第二种工艺中，锌被引入用于制造水泥浆的液相，这通常被称为凝固/稳定。在实验室制造的熟料中，锌主要固定在一种新的化合物(Ca(6)Zn(3)Al（4)O(15)）中。此外，除了硅酸二钙（C(2)S）外，锌在硅酸三钙（C(3)S）和间隙相(C（3)A和C(4)AF）中也存在。在本研究中，阈限值对应于在不改变熟料相稳定性的情况下可以掺入的最大Zn量。当x射线衍射观察到C(3) a含量下降和/或Ca(6)Zn(3)Al(4)O（15）的存在时，达到该阈值。所研究的熟料中锌的阈值为0.7%（重量比）。采用等温量热法研究了掺锌水泥的反应性。这些试验表明，即使锌含量超过阈值（即1%），锌的掺入对硅酸钙水化(C（3)S和C(2)S）没有影响。这些结果与锌在水泥浆中固化/稳定处理得到的结果进行了比较。在这些实验中，锌含量为0.7%会导致水泥水化的显著延迟。这种行为的差异是由于锌离子在溶液中释放的流动较慢，当它被纳入熟料相时。因此，在熟化过程中固定化是处理普通硅酸盐水泥（OPC）中锌含量高的废物的一个很好的选择，而不会对水泥凝结时间造成众所周知的有害影响。(C) 2011 Elsevier Ltd.版权所有。
This study compares two methods to immobilise the same amount of Zn in cement paste. In the first method. Zn is introduced into the raw material before clinkerisation, whereas in the second process, Zn is introduced in the liquid phase used to make the cement paste, which is often referred to as solidification/stabilisation. In laboratory-made clinker, Zn was mainly fixed within a new compound (Ca(6)Zn(3)Al(4)O(15)). Also, Zn was observed in tricalcium silicate (C(3)S) and in the interstitial phase (C(3)A and C(4)AF) with the exception of dicalcium silicate (C(2)S). In the present study, the threshold limit value corresponds to the maximum amount of Zn that could be incorporated without the stability of the clinker phases being modified. This threshold was reached when a decrease in C(3)A content and/or the presence of Ca(6)Zn(3)Al(4)O(15) were observed by X-ray diffraction. The threshold limit of Zn in the studied clinker was established at 0.7% by weight. The reactivity of synthesised cement doped with Zn was studied by isothermal calorimetry measurements. These tests revealed that the incorporation of Zn had no effect on calcium silicate hydration (C(3)S and C(2)S), even if the Zn content exceeded the threshold limit value, i.e., 1%. These results were compared with those obtained through the solidification/stabilisation treatment of Zn in a cement paste. In these experiments, a Zn content of 0.7% induced a significant delay in the cement hydration. This difference in behaviour is due to the slower flow of zinc ions released in solution when it is incorporated in the clinker phases. Thus, the immobilisation during clinkerisation is a good alternative to treat waste with a high Zn content in Ordinary Portland Cement (OPC) without causing the well-known, deleterious effect on cement setting time. (C) 2011 Elsevier Ltd. All rights reserved.