Effects of carbonation on phase composition of Metakaolin-blended cement pastes
Effects of carbonation on phase composition of Metakaolin-blended cement pastes
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碳化对偏高岭土掺混水泥浆体相组成的影响
DOI：
10.1016/j.conbuildmat.2022.126639
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发表时间：
2022-02-04
影响因子：
7.4
通讯作者：
Zhang, Hao
中科院分区：
文献类型：
--
作者：
Chang, Honglei;Wang, Yunfei;Zhang, Hao
为明确碳化对掺偏高岭土（MK）水泥浆体物相评价的影响，采用X射线衍射（XRD）定量分析技术对不同掺量、不同碳化时间的MK水泥浆体的物相组成进行了表征。同时，系统探讨了不同碳酸化产物中Ca的转化规律。结果表明，在加速碳酸化作用下，氢氧化钙和钙矾石急剧减少并迅速消失，而CaCO 3显著增加; CH完全消耗后，C-S-H逐渐碳酸化并大幅减少。此外，根据碳酸化产物中Ca的含量变化，85%以上的CaCO 3是由CH、C-S-H和未水化矿物碳酸化生成的。随着MK用量的增加，CH中Ca的减少量与CaCO 3中Ca的增加量之比逐渐减小，而C-SH中Ca的减少量所占的百分比逐渐增大。在碳酸化初期，CH中Ca的减少占CaCO 3中Ca增加的主要部分，随着碳酸化时间的延长，C-S-H中Ca减少的比例逐渐增大。
To ascertain the impact of carbonation on the phase evaluation of cement paste blended with metakaolin (MK), the phase composition of cement paste with different dosages of MK and at different carbonation time was characterized with X-ray diffraction (XRD) quantitative analysis technology. Meanwhile, the transformation law of Ca in different carbonation products was discussed systemically. The results show that, under accelerated carbonation, calcium hydroxide and Ettringite decrease sharply and disappear quickly, while CaCO3 increases significantly; after the complete consumption of CH, C-S-H is carbonated gradually and decreases greatly. Moreover, based on the content change of Ca in carbonation products, over 85% CaCO3 is generated through the carbonation of CH, C-S-H and unhydrated minerals. With the increase MK dosage, the ratio of the decrement of Ca in CH to the increment of Ca in CaCO3 declines gradually, while the percentage of the decrement of Ca in C-SH grows gradually. Besides, at the early stage of carbonation, the decrement of Ca in CH constitutes the major part of the increment of Ca in CaCO3, and with carbonation time increasing, the proportion of the decrement of Ca in C-S-H rises gradually.